diff --git a/readthedocs/api/v2/views/integrations.py b/readthedocs/api/v2/views/integrations.py
index 7717ab8a17a..6e1c0196a09 100644
--- a/readthedocs/api/v2/views/integrations.py
+++ b/readthedocs/api/v2/views/integrations.py
@@ -20,6 +20,7 @@
 
 from readthedocs.builds.constants import BRANCH
 from readthedocs.builds.constants import LATEST
+from readthedocs.builds.constants import LATEST_VERBOSE_NAME
 from readthedocs.builds.constants import TAG
 from readthedocs.core.signals import webhook_bitbucket
 from readthedocs.core.signals import webhook_github
@@ -313,7 +314,7 @@ def get_closed_external_version_response(self, project):
 
     def update_default_branch(self, default_branch):
         """
-        Update the `Version.identifer` for `latest` with the VCS's `default_branch`.
+        Update the `Version.identifier` for `latest` with the VCS's `default_branch`.
 
         The VCS's `default_branch` is the branch cloned when there is no specific branch specified
         (e.g. `git clone <URL>`).
@@ -335,7 +336,9 @@ def update_default_branch(self, default_branch):
             # Always check for the machine attribute, since latest can be user created.
             # RTD doesn't manage those.
             self.project.versions.filter(slug=LATEST, machine=True).update(
-                identifier=default_branch
+                identifier=default_branch,
+                verbose_name=LATEST_VERBOSE_NAME,
+                type=BRANCH,
             )
 
 
diff --git a/readthedocs/builds/models.py b/readthedocs/builds/models.py
index 24f32c99215..94dd151f9e9 100644
--- a/readthedocs/builds/models.py
+++ b/readthedocs/builds/models.py
@@ -222,6 +222,10 @@ def is_public(self):
     def is_external(self):
         return self.type == EXTERNAL
 
+    @property
+    def is_machine_latest(self):
+        return self.machine and self.slug == LATEST
+
     @property
     def explicit_name(self):
         """
diff --git a/readthedocs/doc_builder/director.py b/readthedocs/doc_builder/director.py
index 11de6c27b4f..aa5df137e94 100644
--- a/readthedocs/doc_builder/director.py
+++ b/readthedocs/doc_builder/director.py
@@ -223,9 +223,26 @@ def checkout(self):
                     dismissable=True,
                 )
 
-        identifier = self.data.build_commit or self.data.version.identifier
-        log.info("Checking out.", identifier=identifier)
-        self.vcs_repository.checkout(identifier)
+        # Get the default branch of the repository if the project doesn't
+        # have an explicit default branch set and we are building latest.
+        # The identifier from latest will be updated with this value
+        # if the build succeeds.
+        is_latest_without_default_branch = (
+            self.data.version.is_machine_latest and not self.data.project.default_branch
+        )
+        if is_latest_without_default_branch:
+            self.data.default_branch = self.data.build_director.vcs_repository.get_default_branch()
+            log.info(
+                "Default branch for the repository detected.",
+                default_branch=self.data.default_branch,
+            )
+
+        # We can skip the checkout step since we just cloned the repository,
+        # and the default branch is already checked out.
+        if not is_latest_without_default_branch:
+            identifier = self.data.build_commit or self.data.version.identifier
+            log.info("Checking out.", identifier=identifier)
+            self.vcs_repository.checkout(identifier)
 
         # The director is responsible for understanding which config file to use for a build.
         # In order to reproduce a build 1:1, we may use readthedocs_yaml_path defined by the build
diff --git a/readthedocs/projects/models.py b/readthedocs/projects/models.py
index 3cbba2315a4..c74c795526d 100644
--- a/readthedocs/projects/models.py
+++ b/readthedocs/projects/models.py
@@ -1175,15 +1175,21 @@ def get_original_latest_version(self):
         When latest is machine created, it's basically an alias
         for the default branch/tag (like main/master),
 
-        Returns None if the current default version doesn't point to a valid version.
+        Returns None if latest doesn't point to a valid version,
+        or if isn't managed by RTD (machine=False).
         """
-        default_version_name = self.get_default_branch()
+        # For latest, the identifier is the name of the branch/tag.
+        latest_version_identifier = (
+            self.versions.filter(slug=LATEST, machine=True)
+            .values_list("identifier", flat=True)
+            .first()
+        )
+        if not latest_version_identifier:
+            return None
         return (
             self.versions(manager=INTERNAL)
             .exclude(slug=LATEST)
-            .filter(
-                verbose_name=default_version_name,
-            )
+            .filter(verbose_name=latest_version_identifier)
             .first()
         )
 
@@ -1201,8 +1207,22 @@ def update_latest_version(self):
             return
 
         # default_branch can be a tag or a branch name!
-        default_version_name = self.get_default_branch()
-        original_latest = self.get_original_latest_version()
+        default_version_name = self.get_default_branch(fallback_to_vcs=False)
+        # If the default_branch is not set, it means that the user
+        # wants to use the default branch of the respository, but
+        # we don't know what that is here, `latest` will be updated
+        # on the next build.
+        if not default_version_name:
+            return
+
+        # Search for a branch or tag with the name of the default branch,
+        # so we can sync latest with it.
+        original_latest = (
+            self.versions(manager=INTERNAL)
+            .exclude(slug=LATEST)
+            .filter(verbose_name=default_version_name)
+            .first()
+        )
         latest.verbose_name = LATEST_VERBOSE_NAME
         latest.type = original_latest.type if original_latest else BRANCH
         # For latest, the identifier is the name of the branch/tag.
@@ -1302,14 +1322,22 @@ def get_default_version(self):
             return self.default_version
         return LATEST
 
-    def get_default_branch(self):
-        """Get the version representing 'latest'."""
+    def get_default_branch(self, fallback_to_vcs=True):
+        """
+        Get the name of the branch or tag that the user wants to use as 'latest'.
+
+        In case the user explicitly set a default branch, we use that,
+        otherwise we try to get it from the remote repository.
+        """
         if self.default_branch:
             return self.default_branch
 
         if self.remote_repository and self.remote_repository.default_branch:
             return self.remote_repository.default_branch
 
+        if not fallback_to_vcs:
+            return None
+
         vcs_class = self.vcs_class()
         if vcs_class:
             return vcs_class.fallback_branch
diff --git a/readthedocs/projects/tasks/builds.py b/readthedocs/projects/tasks/builds.py
index 0735f018c6e..060fe5ea2d3 100644
--- a/readthedocs/projects/tasks/builds.py
+++ b/readthedocs/projects/tasks/builds.py
@@ -27,6 +27,7 @@
 from readthedocs.builds import tasks as build_tasks
 from readthedocs.builds.constants import ARTIFACT_TYPES
 from readthedocs.builds.constants import ARTIFACT_TYPES_WITHOUT_MULTIPLE_FILES_SUPPORT
+from readthedocs.builds.constants import BRANCH
 from readthedocs.builds.constants import BUILD_FINAL_STATES
 from readthedocs.builds.constants import BUILD_STATE_BUILDING
 from readthedocs.builds.constants import BUILD_STATE_CANCELLED
@@ -117,6 +118,10 @@ class TaskData:
     config: BuildConfigV2 = None
     project: APIProject = None
     version: APIVersion = None
+    # Default branch for the repository.
+    # Only set when building the latest version, and the project
+    # doesn't have an explicit default branch.
+    default_branch: str | None = None
 
     # Dictionary returned from the API.
     build: dict = field(default_factory=dict)
@@ -665,18 +670,22 @@ def on_success(self, retval, task_id, args, kwargs):
         # NOTE: we are updating the db version instance *only* when
         # TODO: remove this condition and *always* update the DB Version instance
         if "html" in valid_artifacts:
+            data = {
+                "built": True,
+                "documentation_type": self.data.version.documentation_type,
+                "has_pdf": "pdf" in valid_artifacts,
+                "has_epub": "epub" in valid_artifacts,
+                "has_htmlzip": "htmlzip" in valid_artifacts,
+                "build_data": self.data.version.build_data,
+                "addons": self.data.version.addons,
+            }
+            # Update the latest version to point to the current VCS default branch
+            # if the project doesn't have an explicit default branch set.
+            if self.data.default_branch:
+                data["identifier"] = self.data.default_branch
+                data["type"] = BRANCH
             try:
-                self.data.api_client.version(self.data.version.pk).patch(
-                    {
-                        "built": True,
-                        "documentation_type": self.data.version.documentation_type,
-                        "has_pdf": "pdf" in valid_artifacts,
-                        "has_epub": "epub" in valid_artifacts,
-                        "has_htmlzip": "htmlzip" in valid_artifacts,
-                        "build_data": self.data.version.build_data,
-                        "addons": self.data.version.addons,
-                    }
-                )
+                self.data.api_client.version(self.data.version.pk).patch(data)
             except HttpClientError:
                 # NOTE: I think we should fail the build if we cannot update
                 # the version at this point. Otherwise, we will have inconsistent data
diff --git a/readthedocs/projects/tests/test_build_tasks.py b/readthedocs/projects/tests/test_build_tasks.py
index 51177f88868..23a1fabe969 100644
--- a/readthedocs/projects/tests/test_build_tasks.py
+++ b/readthedocs/projects/tests/test_build_tasks.py
@@ -315,6 +315,8 @@ def test_build_updates_documentation_type(self, load_yaml_config):
             "has_pdf": True,
             "has_epub": True,
             "has_htmlzip": False,
+            "identifier": mock.ANY,
+            "type": "branch",
         }
 
     @pytest.mark.parametrize(
@@ -645,6 +647,8 @@ def test_successful_build(
             "has_pdf": True,
             "has_epub": True,
             "has_htmlzip": True,
+            "identifier": mock.ANY,
+            "type": "branch",
         }
         # Set project has valid clone
         assert self.requests_mock.request_history[9]._request.method == "PATCH"
@@ -940,6 +944,8 @@ def test_successful_build_with_temporary_s3_credentials(
             "has_pdf": True,
             "has_epub": True,
             "has_htmlzip": True,
+            "identifier": mock.ANY,
+            "type": "branch",
         }
         # Set project has valid clone
         assert self.requests_mock.request_history[11]._request.method == "PATCH"
@@ -1106,7 +1112,7 @@ def test_cancelled_build(
         }
 
     @mock.patch("readthedocs.doc_builder.director.load_yaml_config")
-    def test_build_commands_executed(
+    def test_build_commands_executed_latest_version(
         self,
         load_yaml_config,
     ):
@@ -1144,18 +1150,15 @@ def test_build_commands_executed(
                     "--prune-tags",
                     "--depth",
                     "50",
-                    "refs/heads/master:refs/remotes/origin/master",
                 ),
                 mock.call(
                     "git",
-                    "show-ref",
-                    "--verify",
-                    "--quiet",
-                    "--",
-                    "refs/remotes/origin/a1b2c3",
+                    "symbolic-ref",
+                    "--short",
+                    "refs/remotes/origin/HEAD",
+                    demux=True,
                     record=False,
                 ),
-                mock.call("git", "checkout", "--force", "origin/a1b2c3"),
                 mock.call(
                     "git",
                     "ls-remote",
@@ -1386,6 +1389,271 @@ def test_build_commands_executed(
             ]
         )
 
+    @mock.patch("readthedocs.doc_builder.director.load_yaml_config")
+    def test_build_commands_executed_non_machine_version(
+        self,
+        load_yaml_config,
+    ):
+        self.version.machine = False
+        self.version.save()
+
+        load_yaml_config.return_value = get_build_config(
+            {
+                "version": 2,
+                "formats": "all",
+                "sphinx": {
+                    "configuration": "docs/conf.py",
+                },
+            },
+            validate=True,
+        )
+
+        # Create the artifact paths, so it's detected by the builder
+        os.makedirs(self.project.artifact_path(version=self.version.slug, type_="html"))
+        os.makedirs(self.project.artifact_path(version=self.version.slug, type_="json"))
+        os.makedirs(
+            self.project.artifact_path(version=self.version.slug, type_="htmlzip")
+        )
+        os.makedirs(self.project.artifact_path(version=self.version.slug, type_="epub"))
+        os.makedirs(self.project.artifact_path(version=self.version.slug, type_="pdf"))
+
+        self._trigger_update_docs_task()
+
+        self.mocker.mocks["git.Backend.run"].assert_has_calls(
+            [
+                mock.call("git", "clone", "--depth", "1", mock.ANY, "."),
+                mock.call(
+                    "git",
+                    "fetch",
+                    "origin",
+                    "--force",
+                    "--prune",
+                    "--prune-tags",
+                    "--depth",
+                    "50",
+                    "refs/heads/latest:refs/remotes/origin/latest",
+                ),
+                mock.call(
+                    "git",
+                    "show-ref",
+                    "--verify",
+                    "--quiet",
+                    "--",
+                    "refs/remotes/origin/a1b2c3",
+                    record=False,
+                ),
+                mock.call("git", "checkout", "--force", "origin/a1b2c3"),
+                mock.call(
+                    "git",
+                    "ls-remote",
+                    "--tags",
+                    "--heads",
+                    mock.ANY,
+                    demux=True,
+                    record=False,
+                ),
+            ]
+        )
+
+        python_version = settings.RTD_DOCKER_BUILD_SETTINGS["tools"]["python"]["3"]
+        self.mocker.mocks["environment.run"].assert_has_calls(
+            [
+                mock.call("asdf", "install", "python", python_version),
+                mock.call("asdf", "global", "python", python_version),
+                mock.call("asdf", "reshim", "python", record=False),
+                mock.call(
+                    "python",
+                    "-mpip",
+                    "install",
+                    "-U",
+                    "virtualenv",
+                    "setuptools",
+                ),
+                mock.call(
+                    "python",
+                    "-mvirtualenv",
+                    "$READTHEDOCS_VIRTUALENV_PATH",
+                    bin_path=None,
+                    cwd=None,
+                ),
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "pip",
+                    "install",
+                    "--upgrade",
+                    "--no-cache-dir",
+                    "pip",
+                    "setuptools",
+                    bin_path=mock.ANY,
+                    cwd=mock.ANY,
+                ),
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "pip",
+                    "install",
+                    "--upgrade",
+                    "--no-cache-dir",
+                    "sphinx",
+                    bin_path=mock.ANY,
+                    cwd=mock.ANY,
+                ),
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "sphinx",
+                    "-T",
+                    "-b",
+                    "html",
+                    "-d",
+                    "_build/doctrees",
+                    "-D",
+                    "language=en",
+                    ".",
+                    "$READTHEDOCS_OUTPUT/html",
+                    cwd=mock.ANY,
+                    bin_path=mock.ANY,
+                ),
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "sphinx",
+                    "-T",
+                    "-b",
+                    "singlehtml",
+                    "-d",
+                    "_build/doctrees",
+                    "-D",
+                    "language=en",
+                    ".",
+                    "$READTHEDOCS_OUTPUT/htmlzip",
+                    cwd=mock.ANY,
+                    bin_path=mock.ANY,
+                ),
+                mock.call(
+                    "mktemp",
+                    "--directory",
+                    record=False,
+                ),
+                mock.call(
+                    "mv",
+                    mock.ANY,
+                    mock.ANY,
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "mkdir",
+                    "--parents",
+                    mock.ANY,
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "zip",
+                    "--recurse-paths",
+                    "--symlinks",
+                    mock.ANY,
+                    mock.ANY,
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "sphinx",
+                    "-T",
+                    "-b",
+                    "latex",
+                    "-d",
+                    "_build/doctrees",
+                    "-D",
+                    "language=en",
+                    ".",
+                    "$READTHEDOCS_OUTPUT/pdf",
+                    cwd=mock.ANY,
+                    bin_path=mock.ANY,
+                ),
+                mock.call("cat", "latexmkrc", cwd=mock.ANY),
+                # NOTE: pdf `mv` commands and others are not here because the
+                # PDF resulting file is not found in the process (`_post_build`)
+                mock.call(
+                    mock.ANY,
+                    "-m",
+                    "sphinx",
+                    "-T",
+                    "-b",
+                    "epub",
+                    "-d",
+                    "_build/doctrees",
+                    "-D",
+                    "language=en",
+                    ".",
+                    "$READTHEDOCS_OUTPUT/epub",
+                    cwd=mock.ANY,
+                    bin_path=mock.ANY,
+                ),
+                mock.call(
+                    "mv",
+                    mock.ANY,
+                    "/tmp/project-latest.epub",
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "rm",
+                    "--recursive",
+                    "$READTHEDOCS_OUTPUT/epub",
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "mkdir",
+                    "--parents",
+                    "$READTHEDOCS_OUTPUT/epub",
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "mv",
+                    "/tmp/project-latest.epub",
+                    mock.ANY,
+                    cwd=mock.ANY,
+                    record=False,
+                ),
+                mock.call(
+                    "test",
+                    "-x",
+                    "_build/html",
+                    record=False,
+                    cwd=mock.ANY,
+                ),
+                mock.call("lsb_release", "--description", record=False, demux=True),
+                mock.call("python", "--version", record=False, demux=True),
+                mock.call(
+                    "dpkg-query",
+                    "--showformat",
+                    "${package} ${version}\\n",
+                    "--show",
+                    record=False,
+                    demux=True,
+                ),
+                mock.call(
+                    "python",
+                    "-m",
+                    "pip",
+                    "list",
+                    "--pre",
+                    "--local",
+                    "--format",
+                    "json",
+                    record=False,
+                    demux=True,
+                ),
+            ]
+        )
+
     @mock.patch.object(GitHubAppService, "get_clone_token")
     @mock.patch("readthedocs.doc_builder.director.load_yaml_config")
     def test_build_commands_executed_with_clone_token(
@@ -1444,18 +1712,15 @@ def test_build_commands_executed_with_clone_token(
                     "--prune-tags",
                     "--depth",
                     "50",
-                    "refs/heads/master:refs/remotes/origin/master",
                 ),
                 mock.call(
                     "git",
-                    "show-ref",
-                    "--verify",
-                    "--quiet",
-                    "--",
-                    "refs/remotes/origin/a1b2c3",
+                    "symbolic-ref",
+                    "--short",
+                    "refs/remotes/origin/HEAD",
+                    demux=True,
                     record=False,
                 ),
-                mock.call("git", "checkout", "--force", "origin/a1b2c3"),
                 mock.call(
                     "git",
                     "ls-remote",
diff --git a/readthedocs/proxito/tests/test_hosting.py b/readthedocs/proxito/tests/test_hosting.py
index 13157608f98..8d013ab8294 100644
--- a/readthedocs/proxito/tests/test_hosting.py
+++ b/readthedocs/proxito/tests/test_hosting.py
@@ -408,7 +408,7 @@ def test_number_of_queries_versions_with_downloads(self):
                 active=True,
             )
 
-        with self.assertNumQueries(13):
+        with self.assertNumQueries(14):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -851,7 +851,7 @@ def test_number_of_queries_project_version_slug(self):
                 active=True,
             )
 
-        with self.assertNumQueries(14):
+        with self.assertNumQueries(16):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -880,7 +880,7 @@ def test_number_of_queries_url(self):
                 active=True,
             )
 
-        with self.assertNumQueries(15):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -932,7 +932,7 @@ def test_number_of_queries_url_subproject(self):
         assert r.status_code == 200
 
         # Test parent project has fewer queries
-        with self.assertNumQueries(14):
+        with self.assertNumQueries(16):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -958,7 +958,7 @@ def test_number_of_queries_url_translations(self):
                 language=language,
             )
 
-        with self.assertNumQueries(24):
+        with self.assertNumQueries(26):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -1108,7 +1108,7 @@ def test_file_tree_diff(self, get_manifest):
                 ],
             ),
         ]
-        with self.assertNumQueries(19):
+        with self.assertNumQueries(20):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
diff --git a/readthedocs/rtd_tests/tests/test_backend.py b/readthedocs/rtd_tests/tests/test_backend.py
index dd825d981b8..d403208d868 100644
--- a/readthedocs/rtd_tests/tests/test_backend.py
+++ b/readthedocs/rtd_tests/tests/test_backend.py
@@ -146,6 +146,26 @@ def test_git_lsremote_branches_only(self):
             {branch.verbose_name: branch.identifier for branch in repo_branches},
         )
 
+    def test_get_default_branch(self):
+        version = self.project.versions.first()
+        repo = self.project.vcs_repo(environment=self.build_environment, version=version)
+        repo.update()
+        default_branch = repo.get_default_branch()
+        assert default_branch == "master"
+
+        version = get(
+            Version,
+            project=self.project,
+            type=BRANCH,
+            identifier="submodule",
+            verbose_name="submodule",
+        )
+        repo = self.project.vcs_repo(environment=self.build_environment, version=version)
+        repo.update()
+        repo.checkout("submodule")
+        default_branch = repo.get_default_branch()
+        assert default_branch == "master"
+
     def test_git_update_and_checkout(self):
         version = self.project.versions.first()
         repo = self.project.vcs_repo(environment=self.build_environment, version=version)
diff --git a/readthedocs/rtd_tests/tests/test_sync_versions.py b/readthedocs/rtd_tests/tests/test_sync_versions.py
index d7339f28cfa..e6f5195c9c5 100644
--- a/readthedocs/rtd_tests/tests/test_sync_versions.py
+++ b/readthedocs/rtd_tests/tests/test_sync_versions.py
@@ -294,7 +294,10 @@ def test_update_latest_version_type(self):
         self.assertEqual(latest_version.verbose_name, "latest")
         self.assertEqual(latest_version.machine, False)
 
-        # Latest is back as machine created, and as a branch.
+        # Latest is back as machine created,
+        # but its type and identifier are not changed,
+        # as the user doesn't have a default branch set.
+        # The correct identifier and type will be set on the next build.
         sync_versions_task(
             self.pip.pk,
             branches_data=branches_data,
@@ -303,8 +306,8 @@ def test_update_latest_version_type(self):
 
         latest_version = self.pip.versions.get(slug=LATEST)
         self.assertIsNone(self.pip.default_branch)
-        self.assertEqual(latest_version.type, BRANCH)
-        self.assertEqual(latest_version.identifier, "master")
+        self.assertEqual(latest_version.type, TAG)
+        self.assertEqual(latest_version.identifier, "abc123")
         self.assertEqual(latest_version.verbose_name, "latest")
         self.assertEqual(latest_version.machine, True)
 
@@ -729,7 +732,7 @@ def test_machine_attr_when_user_define_latest_tag_and_delete_it(self):
 
         branches_data = [
             {
-                "identifier": "origin/master",
+                "identifier": "master",
                 "verbose_name": "master",
             },
         ]
@@ -757,7 +760,7 @@ def test_machine_attr_when_user_define_latest_tag_and_delete_it(self):
         # Deleting the tag should return the RTD's latest
         branches_data = [
             {
-                "identifier": "origin/master",
+                "identifier": "master",
                 "verbose_name": "master",
             },
         ]
@@ -768,12 +771,15 @@ def test_machine_attr_when_user_define_latest_tag_and_delete_it(self):
             tags_data=[],
         )
 
-        # The latest isn't stuck with the previous commit
+        # latest isn't stuck with the previous commit,
+        # but its type and identifier are not changed,
+        # as the user doesn't have a default branch set.
+        # The correct identifier and type will be set on the next build.
         version_latest = self.pip.versions.get(slug="latest")
         self.assertIsNone(self.pip.default_branch)
         self.assertTrue(version_latest.machine)
         self.assertEqual(
-            "master",
+            "1abc2def3",
             version_latest.identifier,
         )
         self.assertTrue(version_latest.machine)
@@ -801,20 +807,20 @@ def test_machine_attr_when_user_define_latest_tag_and_delete_it(self):
         self.assertEqual(version_latest.type, TAG)
 
     def test_machine_attr_when_user_define_latest_branch_and_delete_it(self):
-        """The user creates a branch named ``latest`` on an existing repo, when
-        syncing the versions, the RTD's ``latest`` is lost (set to
-                                                            machine=False) and doesn't update automatically anymore, when the branch
-        is deleted on the user repository, the RTD's ``latest`` is back (set to
-                                                                         machine=True).
+        """
+        The user creates a branch named ``latest`` on an existing repo, when
+        syncing the versions, the RTD's ``latest`` is lost (set to machine=False)
+        and doesn't update automatically anymore, when the branch is deleted on
+        the user repository, the RTD's ``latest`` is back (set to machine=True).
         """
         branches_data = [
             {
-                "identifier": "origin/master",
+                "identifier": "master",
                 "verbose_name": "master",
             },
             # User new latest
             {
-                "identifier": "origin/latest",
+                "identifier": "latest",
                 "verbose_name": "latest",
             },
         ]
@@ -830,14 +836,14 @@ def test_machine_attr_when_user_define_latest_branch_and_delete_it(self):
         self.assertIsNone(self.pip.default_branch)
         self.assertFalse(version_latest.machine)
         self.assertEqual(
-            "origin/latest",
+            "latest",
             version_latest.identifier,
         )
 
         # Deleting the branch should return the RTD's latest
         branches_data = [
             {
-                "identifier": "origin/master",
+                "identifier": "master",
                 "verbose_name": "master",
             },
         ]
@@ -848,12 +854,15 @@ def test_machine_attr_when_user_define_latest_branch_and_delete_it(self):
             tags_data=[],
         )
 
-        # The latest isn't stuck with the previous branch
+        # The latest isn't stuck with the previous branch,
+        # but the identifier is still `latest`,
+        # as the user doesn't have a default branch set.
+        # The correct identifier will be set on the next build.
         version_latest = self.pip.versions.get(slug="latest")
         self.assertIsNone(self.pip.default_branch)
         self.assertTrue(version_latest.machine)
         self.assertEqual(
-            "master",
+            "latest",
             version_latest.identifier,
         )
         self.assertTrue(version_latest.machine)
@@ -861,11 +870,11 @@ def test_machine_attr_when_user_define_latest_branch_and_delete_it(self):
         # Test with an explicit default branch.
         branches_data = [
             {
-                "identifier": "origin/master",
+                "identifier": "master",
                 "verbose_name": "master",
             },
             {
-                "identifier": "origin/default-branch",
+                "identifier": "default-branch",
                 "verbose_name": "default-branch",
             },
         ]
diff --git a/readthedocs/vcs_support/backends/git.py b/readthedocs/vcs_support/backends/git.py
index 3c994d96b28..01a58f3ff95 100644
--- a/readthedocs/vcs_support/backends/git.py
+++ b/readthedocs/vcs_support/backends/git.py
@@ -291,12 +291,15 @@ def fetch(self):
             "--depth",
             str(self.repo_depth),
         ]
-        remote_reference = self.get_remote_fetch_refspec()
-
-        if remote_reference:
-            # TODO: We are still fetching the latest 50 commits.
-            # A PR might have another commit added after the build has started...
-            cmd.append(remote_reference)
+        # Skip adding a remote reference if we are building "latest",
+        # and the user hasn't defined a default branch (which means we need to use the default branch from the repo).
+        omit_remote_reference = self.version.is_machine_latest and not self.project.default_branch
+        if not omit_remote_reference:
+            remote_reference = self.get_remote_fetch_refspec()
+            if remote_reference:
+                # TODO: We are still fetching the latest 50 commits.
+                # A PR might have another commit added after the build has started...
+                cmd.append(remote_reference)
 
         # Log a warning, except for machine versions since it's a known bug that
         # we haven't stored a remote refspec in Version for those "stable" versions.
@@ -388,6 +391,25 @@ def checkout_revision(self, revision):
                 },
             ) from exc
 
+    def get_default_branch(self):
+        """
+        Return the default branch of the repository.
+
+        The default branch is the branch that is checked out when cloning the
+        repository. This is usually master or main, it can be configured
+        in the repository settings.
+
+        The ``git symbolic-ref`` command will produce an output like:
+
+        .. code-block:: text
+
+           origin/main
+        """
+        cmd = ["git", "symbolic-ref", "--short", "refs/remotes/origin/HEAD"]
+        _, stdout, _ = self.run(*cmd, demux=True, record=False)
+        default_branch = stdout.strip().removeprefix("origin/")
+        return default_branch
+
     def lsremote(self, include_tags=True, include_branches=True):
         """
         Use ``git ls-remote`` to list branches and tags without cloning the repository.