diff --git a/src/sentry/integrations/base.py b/src/sentry/integrations/base.py
index 5f9ebe1d376c70..ba6c2aa1ea2758 100644
--- a/src/sentry/integrations/base.py
+++ b/src/sentry/integrations/base.py
@@ -527,7 +527,7 @@ def message_from_error(self, exc: Exception) -> str:
         elif isinstance(exc, UnsupportedResponseType):
             return ERR_UNSUPPORTED_RESPONSE_TYPE.format(content_type=exc.content_type)
         elif isinstance(exc, ApiError):
-            if exc.json:
+            if exc.json and isinstance(exc.json, dict):
                 msg = self.error_message_from_json(exc.json) or "unknown error"
             else:
                 msg = "unknown error"
diff --git a/src/sentry/integrations/gitlab/integration.py b/src/sentry/integrations/gitlab/integration.py
index ab6608d764bd77..2ca39e53ffd865 100644
--- a/src/sentry/integrations/gitlab/integration.py
+++ b/src/sentry/integrations/gitlab/integration.py
@@ -186,6 +186,14 @@ def get_repositories(
             # Note: gitlab projects are the same things as repos everywhere else
             group = self.get_group_id()
             resp = self.get_client().search_projects(group, query)
+            # GitLab returns {"status": "error", ...} when the group is
+            # inaccessible. The pagination layer turns that dict into a list
+            # of its keys (e.g. ["status", "error"]), which would crash the
+            # list comprehension below with TypeError on str["id"].
+            if resp and not isinstance(resp[0], dict):
+                raise IntegrationError(
+                    "Expected list of projects from GitLab, got unexpected response"
+                )
             instance = self.model.metadata["instance"]
             return [
                 {
diff --git a/tests/sentry/integrations/source_code_management/test_sync_repos.py b/tests/sentry/integrations/source_code_management/test_sync_repos.py
index 8f5c3498ce60da..57cda27f154b89 100644
--- a/tests/sentry/integrations/source_code_management/test_sync_repos.py
+++ b/tests/sentry/integrations/source_code_management/test_sync_repos.py
@@ -10,6 +10,7 @@
 from sentry.constants import ObjectStatus
 from sentry.integrations.github.integration import GitHubIntegrationProvider
 from sentry.integrations.github_enterprise.integration import GitHubEnterpriseIntegrationProvider
+from sentry.integrations.gitlab.integration import GitlabIntegration
 from sentry.integrations.models.organization_integration import OrganizationIntegration
 from sentry.integrations.source_code_management.sync_repos import (
     sync_repos_for_org,
@@ -572,6 +573,40 @@ def test_creates_new_repos_for_gitlab(self) -> None:
         assert len(repos) == 2
         assert repos[0].provider == "integrations:gitlab"
 
+    @responses.activate
+    def test_error_dict_response_raises_integration_error(self) -> None:
+        integration = self.create_provider_integration(
+            provider="gitlab",
+            name="Example Gitlab 2",
+            external_id="example2.gitlab.com:group-y",
+            metadata={
+                "instance": "example.gitlab.com",
+                "base_url": "https://example.gitlab.com",
+                "domain_name": "example.gitlab.com/group-y",
+                "verify_ssl": False,
+                "group_id": 1,
+                "webhook_secret": "secret123",
+            },
+        )
+        identity = Identity.objects.create(
+            idp=self.create_identity_provider(type="gitlab", config={}),
+            user=self.user,
+            external_id="gitlab456",
+            data={"access_token": "123456789"},
+        )
+        integration.add_organization(self.organization, self.user, identity.id)
+        installation = integration.get_installation(organization_id=self.organization.id)
+
+        responses.add(
+            responses.GET,
+            "https://example.gitlab.com/api/v4/groups/1/projects?search=&simple=True&include_subgroups=False&page=1&per_page=100&order_by=last_activity_at",
+            json={"status": "error", "error": "group not accessible"},
+        )
+
+        assert isinstance(installation, GitlabIntegration)
+        with pytest.raises(IntegrationError, match="Expected list of projects"):
+            installation.get_repositories()
+
 
 @control_silo_test
 class SyncReposForOrgBitbucketTestCase(TestCase):
@@ -762,6 +797,21 @@ def _wrap_identity_not_valid(*args: object, **kwargs: object) -> None:
         with assume_test_silo_mode(SiloMode.CELL):
             assert Repository.objects.count() == 0
 
+    def test_vsts_message_from_error_handles_string_json(self) -> None:
+        integration = self.create_provider_integration(
+            provider="vsts",
+            external_id="vsts-account-id-2",
+            name="MyVSTSAccount",
+            metadata={"domain_name": "https://myvstsaccount.visualstudio.com/"},
+        )
+        integration.add_organization(self.organization, self.user)
+        installation = integration.get_installation(organization_id=self.organization.id)
+
+        exc = ApiForbiddenError("ADO OAuth tokens disabled")
+        exc.json = "ADO OAuth tokens disabled"  # type: ignore[assignment]
+        msg = installation.message_from_error(exc)
+        assert "unknown error" in msg
+
 
 @control_silo_test
 class SyncReposForOrgBrokenIdentityTestCase(TestCase):