diff --git a/.github/workflows/jit.yml b/.github/workflows/jit.yml
index 52f7d0d2b3df95..80e4ae603a2614 100644
--- a/.github/workflows/jit.yml
+++ b/.github/workflows/jit.yml
@@ -134,6 +134,34 @@ jobs:
           make all --jobs 4
           ./python -m test --multiprocess 0 --timeout 4500 --verbose2 --verbose3
 
+  jit-with-disabled-gil:
+    name: Free-Threaded (Debug)
+    needs: interpreter
+    runs-on: ubuntu-24.04
+    timeout-minutes: 90
+    strategy:
+      fail-fast: false
+      matrix:
+        llvm:
+          - 19
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - name: Build with JIT enabled and GIL disabled
+        run: |
+          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh ${{ matrix.llvm }}
+          export PATH="$(llvm-config-${{ matrix.llvm }} --bindir):$PATH"
+          ./configure --enable-experimental-jit --with-pydebug --disable-gil
+          make all --jobs 4
+      - name: Run tests
+        run: |
+          ./python -m test --multiprocess 0 --timeout 4500 --verbose2 --verbose3
+        continue-on-error: true
+
   no-opt-jit:
     name: JIT without optimizations (Debug)
     needs: interpreter
@@ -160,31 +188,3 @@ jobs:
       - name: Run tests without optimizations
         run: |
           PYTHON_UOPS_OPTIMIZE=0 ./python -m test --multiprocess 0 --timeout 4500 --verbose2 --verbose3
-
-  # XXX: GH-133171
-  # jit-with-disabled-gil:
-  #   name: Free-Threaded (Debug)
-  #   needs: interpreter
-  #   runs-on: ubuntu-24.04
-  #   timeout-minutes: 90
-  #   strategy:
-  #     fail-fast: false
-  #     matrix:
-  #       llvm:
-  #         - 19
-  #   steps:
-  #     - uses: actions/checkout@v4
-  #       with:
-  #         persist-credentials: false
-  #     - uses: actions/setup-python@v5
-  #       with:
-  #         python-version: '3.11'
-  #     - name: Build with JIT enabled and GIL disabled
-  #       run: |
-  #         sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh ${{ matrix.llvm }}
-  #         export PATH="$(llvm-config-${{ matrix.llvm }} --bindir):$PATH"
-  #         ./configure --enable-experimental-jit --with-pydebug --disable-gil
-  #         make all --jobs 4
-  #     - name: Run tests
-  #       run: |
-  #         ./python -m test --multiprocess 0 --timeout 4500 --verbose2 --verbose3
diff --git a/Doc/c-api/weakref.rst b/Doc/c-api/weakref.rst
index c3c6cf413dcef5..14ec9d951c4a5f 100644
--- a/Doc/c-api/weakref.rst
+++ b/Doc/c-api/weakref.rst
@@ -64,30 +64,6 @@ as much as it can.
    .. versionadded:: 3.13
 
 
-.. c:function:: PyObject* PyWeakref_GetObject(PyObject *ref)
-
-   Return a :term:`borrowed reference` to the referenced object from a weak
-   reference, *ref*.  If the referent is no longer live, returns ``Py_None``.
-
-   .. note::
-
-      This function returns a :term:`borrowed reference` to the referenced object.
-      This means that you should always call :c:func:`Py_INCREF` on the object
-      except when it cannot be destroyed before the last usage of the borrowed
-      reference.
-
-   .. deprecated-removed:: 3.13 3.15
-      Use :c:func:`PyWeakref_GetRef` instead.
-
-
-.. c:function:: PyObject* PyWeakref_GET_OBJECT(PyObject *ref)
-
-   Similar to :c:func:`PyWeakref_GetObject`, but does no error checking.
-
-   .. deprecated-removed:: 3.13 3.15
-      Use :c:func:`PyWeakref_GetRef` instead.
-
-
 .. c:function:: int PyWeakref_IsDead(PyObject *ref)
 
    Test if the weak reference *ref* is dead. Returns 1 if the reference is
diff --git a/Doc/data/refcounts.dat b/Doc/data/refcounts.dat
index 144c5608e07426..44ee2586301259 100644
--- a/Doc/data/refcounts.dat
+++ b/Doc/data/refcounts.dat
@@ -2947,12 +2947,6 @@ PyWeakref_CheckProxy:PyObject*:ob:0:
 PyWeakref_CheckRef:int:::
 PyWeakref_CheckRef:PyObject*:ob:0:
 
-PyWeakref_GET_OBJECT:PyObject*::0:
-PyWeakref_GET_OBJECT:PyObject*:ref:0:
-
-PyWeakref_GetObject:PyObject*::0:
-PyWeakref_GetObject:PyObject*:ref:0:
-
 PyWeakref_GetRef:int:::
 PyWeakref_GetRef:PyObject*:ref:0:
 PyWeakref_GetRef:PyObject**:pobj:+1:
diff --git a/Doc/data/stable_abi.dat b/Doc/data/stable_abi.dat
index 3f51254494c654..7ad5f3ecfab5b4 100644
--- a/Doc/data/stable_abi.dat
+++ b/Doc/data/stable_abi.dat
@@ -830,7 +830,6 @@ member,PyVarObject.ob_size,3.2,,
 func,PyVectorcall_Call,3.12,,
 func,PyVectorcall_NARGS,3.12,,
 type,PyWeakReference,3.2,,opaque
-func,PyWeakref_GetObject,3.2,,
 func,PyWeakref_GetRef,3.13,,
 func,PyWeakref_NewProxy,3.2,,
 func,PyWeakref_NewRef,3.2,,
diff --git a/Doc/deprecations/c-api-pending-removal-in-3.15.rst b/Doc/deprecations/c-api-pending-removal-in-3.15.rst
index 8db3631cab31f1..9927b876760d34 100644
--- a/Doc/deprecations/c-api-pending-removal-in-3.15.rst
+++ b/Doc/deprecations/c-api-pending-removal-in-3.15.rst
@@ -3,7 +3,7 @@ Pending removal in Python 3.15
 
 * The :c:func:`!PyImport_ImportModuleNoBlock`:
   Use :c:func:`PyImport_ImportModule` instead.
-* :c:func:`PyWeakref_GetObject` and :c:func:`PyWeakref_GET_OBJECT`:
+* :c:func:`!PyWeakref_GetObject` and :c:func:`!PyWeakref_GET_OBJECT`:
   Use :c:func:`PyWeakref_GetRef` instead. The `pythoncapi-compat project
   <https://github.com/python/pythoncapi-compat/>`__ can be used to get
   :c:func:`PyWeakref_GetRef` on Python 3.12 and older.
diff --git a/Doc/howto/free-threading-extensions.rst b/Doc/howto/free-threading-extensions.rst
index 577e283bb9cb4c..3776132c685414 100644
--- a/Doc/howto/free-threading-extensions.rst
+++ b/Doc/howto/free-threading-extensions.rst
@@ -173,9 +173,9 @@ that return :term:`strong references <strong reference>`.
 +-----------------------------------+-----------------------------------+
 | :c:func:`PyDict_Next`             | none (see :ref:`PyDict_Next`)     |
 +-----------------------------------+-----------------------------------+
-| :c:func:`PyWeakref_GetObject`     | :c:func:`PyWeakref_GetRef`        |
+| :c:func:`!PyWeakref_GetObject`    | :c:func:`PyWeakref_GetRef`        |
 +-----------------------------------+-----------------------------------+
-| :c:func:`PyWeakref_GET_OBJECT`    | :c:func:`PyWeakref_GetRef`        |
+| :c:func:`!PyWeakref_GET_OBJECT`   | :c:func:`PyWeakref_GetRef`        |
 +-----------------------------------+-----------------------------------+
 | :c:func:`PyImport_AddModule`      | :c:func:`PyImport_AddModuleRef`   |
 +-----------------------------------+-----------------------------------+
diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index 90a695ef937f75..8c5c87a7ef16e4 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -1339,7 +1339,7 @@ particular, the following variants typically exist:
 +-----------------+--------------------------------+--------------------------------+
 | utf_8           | U8, UTF, utf8, cp65001         | all languages                  |
 +-----------------+--------------------------------+--------------------------------+
-| utf_8_sig       |                                | all languages                  |
+| utf_8_sig       | utf8-sig                       | all languages                  |
 +-----------------+--------------------------------+--------------------------------+
 
 .. versionchanged:: 3.4
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
index 2dd205dd2b8831..a095d887352127 100644
--- a/Doc/whatsnew/3.11.rst
+++ b/Doc/whatsnew/3.11.rst
@@ -2673,7 +2673,7 @@ Removed
 
   (Contributed by Victor Stinner in :issue:`45474`.)
 
-* Exclude :c:func:`PyWeakref_GET_OBJECT` from the limited C API. It never
+* Exclude :c:func:`!PyWeakref_GET_OBJECT` from the limited C API. It never
   worked since the :c:type:`!PyWeakReference` structure is opaque in the
   limited C API.
   (Contributed by Victor Stinner in :issue:`35134`.)
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index 67fec4ebc4a234..fbb27adbf9969c 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -2246,7 +2246,7 @@ New Features
   (Contributed by Serhiy Storchaka in :gh:`110289`.)
 
 * Add the :c:func:`PyWeakref_GetRef` function
-  as an alternative to  :c:func:`PyWeakref_GetObject`
+  as an alternative to  :c:func:`!PyWeakref_GetObject`
   that returns a :term:`strong reference`
   or ``NULL`` if the referent is no longer live.
   (Contributed by Victor Stinner in :gh:`105927`.)
@@ -2531,8 +2531,8 @@ Deprecated C APIs
   are just aliases to :c:type:`!wchar_t`.
   (Contributed by Victor Stinner in :gh:`105156`.)
 
-* Deprecate the :c:func:`PyWeakref_GetObject` and
-  :c:func:`PyWeakref_GET_OBJECT` functions,
+* Deprecate the :c:func:`!PyWeakref_GetObject` and
+  :c:func:`!PyWeakref_GET_OBJECT` functions,
   which return a :term:`borrowed reference`.
   Replace them with the new :c:func:`PyWeakref_GetRef` function,
   which returns a :term:`strong reference`.
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 7b146621dddcfa..d5d387d9a0aaa7 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -869,6 +869,11 @@ Removed C APIs
   of :c:func:`PyImport_ImportModule`.
   (Contributed by Bénédikt Tran in :gh:`133644`.)
 
+* :c:func:`!PyWeakref_GetObject` and :c:macro:`!PyWeakref_GET_OBJECT`:
+  use :c:func:`PyWeakref_GetRef` instead. The |pythoncapi_compat_project|
+  can be used to get :c:func:`!PyWeakref_GetRef` on Python 3.12 and older.
+  (Contributed by Bénédikt Tran in :gh:`133644`.)
+
 * Remove deprecated :c:func:`!PySys_ResetWarnOptions`.
   Clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
 
diff --git a/Include/cpython/weakrefobject.h b/Include/cpython/weakrefobject.h
index da8e77cddaca63..e0711407cee470 100644
--- a/Include/cpython/weakrefobject.h
+++ b/Include/cpython/weakrefobject.h
@@ -47,20 +47,3 @@ PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
 
 // Test if a weak reference is dead.
 PyAPI_FUNC(int) PyWeakref_IsDead(PyObject *ref);
-
-Py_DEPRECATED(3.13) static inline PyObject* PyWeakref_GET_OBJECT(PyObject *ref_obj)
-{
-    PyWeakReference *ref = _PyWeakref_CAST(ref_obj);
-    PyObject *obj = ref->wr_object;
-    // Explanation for the Py_REFCNT() check: when a weakref's target is part
-    // of a long chain of deallocations which triggers the trashcan mechanism,
-    // clearing the weakrefs can be delayed long after the target's refcount
-    // has dropped to zero.  In the meantime, code accessing the weakref will
-    // be able to "see" the target object even though it is supposed to be
-    // unreachable.  See issue gh-60806.
-    if (Py_REFCNT(obj) > 0) {
-        return obj;
-    }
-    return Py_None;
-}
-#define PyWeakref_GET_OBJECT(ref) PyWeakref_GET_OBJECT(_PyObject_CAST(ref))
diff --git a/Include/internal/pycore_stackref.h b/Include/internal/pycore_stackref.h
index c4e8f10fe05276..062834368bcd29 100644
--- a/Include/internal/pycore_stackref.h
+++ b/Include/internal/pycore_stackref.h
@@ -464,6 +464,12 @@ PyStackRef_CLOSE_SPECIALIZED(_PyStackRef ref, destructor destruct)
     PyStackRef_CLOSE(ref);
 }
 
+static inline int
+PyStackRef_RefcountOnObject(_PyStackRef ref)
+{
+    return (ref.bits & Py_TAG_REFCNT) == 0;
+}
+
 static inline _PyStackRef
 PyStackRef_DUP(_PyStackRef stackref)
 {
diff --git a/Include/weakrefobject.h b/Include/weakrefobject.h
index a6e71eb178b124..17fac62961c0fb 100644
--- a/Include/weakrefobject.h
+++ b/Include/weakrefobject.h
@@ -27,7 +27,6 @@ PyAPI_FUNC(PyObject *) PyWeakref_NewRef(PyObject *ob,
                                         PyObject *callback);
 PyAPI_FUNC(PyObject *) PyWeakref_NewProxy(PyObject *ob,
                                           PyObject *callback);
-Py_DEPRECATED(3.13) PyAPI_FUNC(PyObject *) PyWeakref_GetObject(PyObject *ref);
 
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030D0000
 PyAPI_FUNC(int) PyWeakref_GetRef(PyObject *ref, PyObject **pobj);
diff --git a/Lib/encodings/aliases.py b/Lib/encodings/aliases.py
index 474d74ea3dc191..f4b1b8dd43f920 100644
--- a/Lib/encodings/aliases.py
+++ b/Lib/encodings/aliases.py
@@ -17,7 +17,7 @@
 """
 aliases = {
 
-    # Please keep this list sorted alphabetically by value !
+    # Please keep this list sorted alphabetically by value!
 
     # ascii codec
     '646'                : 'ascii',
@@ -554,6 +554,9 @@
     'utf8_ucs4'          : 'utf_8',
     'cp65001'            : 'utf_8',
 
+    # utf_8_sig codec
+    'utf8_sig'           : 'utf_8_sig',
+
     # uu_codec codec
     'uu'                 : 'uu_codec',
 
diff --git a/Lib/pdb.py b/Lib/pdb.py
index a783583a2b1c38..fd48882e28fe7c 100644
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -100,7 +100,6 @@
 import _pyrepl.utils
 
 from contextlib import ExitStack, closing, contextmanager
-from rlcompleter import Completer
 from types import CodeType
 from warnings import deprecated
 
@@ -364,6 +363,15 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
             readline.set_completer_delims(' \t\n`@#%^&*()=+[{]}\\|;:\'",<>?')
         except ImportError:
             pass
+
+        # GH-138860
+        # We need to lazy-import rlcompleter to avoid deadlock
+        # We cannot import it during self.complete* methods because importing
+        # rlcompleter for the first time will overwrite readline's completer
+        # So we import it here and save the Completer class
+        from rlcompleter import Completer
+        self.RlCompleter = Completer
+
         self.allow_kbdint = False
         self.nosigint = nosigint
         # Consider these characters as part of the command so when the users type
@@ -1186,10 +1194,9 @@ def completedefault(self, text, line, begidx, endidx):
             conv_vars = self.curframe.f_globals.get('__pdb_convenience_variables', {})
             return [f"${name}" for name in conv_vars if name.startswith(text[1:])]
 
-        # Use rlcompleter to do the completion
         state = 0
         matches = []
-        completer = Completer(self.curframe.f_globals | self.curframe.f_locals)
+        completer = self.RlCompleter(self.curframe.f_globals | self.curframe.f_locals)
         while (match := completer.complete(text, state)) is not None:
             matches.append(match)
             state += 1
@@ -1204,8 +1211,8 @@ def _enable_rlcompleter(self, ns):
             return
 
         try:
+            completer = self.RlCompleter(ns)
             old_completer = readline.get_completer()
-            completer = Completer(ns)
             readline.set_completer(completer.complete)
             yield
         finally:
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index 6b74e21ad73d1a..9a7d855003551a 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -4688,6 +4688,28 @@ def foo():
         stdout, _ = self._run_script(script, commands)
         self.assertIn("42", stdout)
 
+    def test_readline_not_imported(self):
+        """GH-138860
+        Directly or indirectly importing readline might deadlock a subprocess
+        if it's launched with process_group=0 or preexec_fn=setpgrp
+
+        It's also a pattern that readline is never imported with just import pdb.
+
+        This test is to ensure that readline is not imported for import pdb.
+        It's possible that we have a good reason to do that in the future.
+        """
+
+        script = textwrap.dedent("""
+            import sys
+            import pdb
+            if "readline" in sys.modules:
+                print("readline imported")
+        """)
+        commands = ""
+        stdout, stderr = self._run_script(script, commands)
+        self.assertNotIn("readline imported", stdout)
+        self.assertEqual(stderr, "")
+
 
 @support.force_colorized_test_class
 class PdbTestColorize(unittest.TestCase):
diff --git a/Misc/NEWS.d/3.11.0a2.rst b/Misc/NEWS.d/3.11.0a2.rst
index 48cf2c1e428d87..12e03b46db0b3f 100644
--- a/Misc/NEWS.d/3.11.0a2.rst
+++ b/Misc/NEWS.d/3.11.0a2.rst
@@ -1188,7 +1188,7 @@ context objects can now be disabled.
 .. nonce: Z0Zk_m
 .. section: C API
 
-Exclude :c:func:`PyWeakref_GET_OBJECT` from the limited C API. It never
+Exclude :c:func:`!PyWeakref_GET_OBJECT` from the limited C API. It never
 worked since the :c:type:`!PyWeakReference` structure is opaque in the
 limited C API.
 
diff --git a/Misc/NEWS.d/3.13.0a1.rst b/Misc/NEWS.d/3.13.0a1.rst
index a3aa7353a1bba1..a5f0161e8f591e 100644
--- a/Misc/NEWS.d/3.13.0a1.rst
+++ b/Misc/NEWS.d/3.13.0a1.rst
@@ -6458,8 +6458,8 @@ Victor Stinner.
 .. nonce: GRxZtI
 .. section: C API
 
-Deprecate the :c:func:`PyWeakref_GetObject` and
-:c:func:`PyWeakref_GET_OBJECT` functions: use the new
+Deprecate the :c:func:`!PyWeakref_GetObject` and
+:c:func:`!PyWeakref_GET_OBJECT` functions: use the new
 :c:func:`PyWeakref_GetRef` function instead. Patch by Victor Stinner.
 
 ..
@@ -6470,7 +6470,7 @@ Deprecate the :c:func:`PyWeakref_GetObject` and
 .. section: C API
 
 Add :c:func:`PyWeakref_GetRef` function: similar to
-:c:func:`PyWeakref_GetObject` but returns a :term:`strong reference`, or
+:c:func:`!PyWeakref_GetObject` but returns a :term:`strong reference`, or
 ``NULL`` if the referent is no longer live. Patch by Victor Stinner.
 
 ..
diff --git a/Misc/NEWS.d/next/C_API/2025-05-08-12-40-59.gh-issue-133644.FNexLJ.rst b/Misc/NEWS.d/next/C_API/2025-05-08-12-40-59.gh-issue-133644.FNexLJ.rst
new file mode 100644
index 00000000000000..71f1eaa5290d46
--- /dev/null
+++ b/Misc/NEWS.d/next/C_API/2025-05-08-12-40-59.gh-issue-133644.FNexLJ.rst
@@ -0,0 +1,3 @@
+Remove deprecated function :c:func:`!PyWeakref_GetObject` and macro
+:c:macro:`!PyWeakref_GET_OBJECT`. Use :c:func:`PyWeakref_GetRef` instead.
+Patch by Bénédikt Tran.
diff --git a/Misc/NEWS.d/next/Library/2025-07-11-08-15-17.gh-issue-83336.ptpmq7.rst b/Misc/NEWS.d/next/Library/2025-07-11-08-15-17.gh-issue-83336.ptpmq7.rst
new file mode 100644
index 00000000000000..022ff664ed94df
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-07-11-08-15-17.gh-issue-83336.ptpmq7.rst
@@ -0,0 +1 @@
+``utf8_sig`` is now aliased to :mod:`encodings.utf_8_sig`
diff --git a/Misc/NEWS.d/next/Library/2025-09-20-17-50-31.gh-issue-138860.Y9JXap.rst b/Misc/NEWS.d/next/Library/2025-09-20-17-50-31.gh-issue-138860.Y9JXap.rst
new file mode 100644
index 00000000000000..0903eb71ae4346
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-09-20-17-50-31.gh-issue-138860.Y9JXap.rst
@@ -0,0 +1 @@
+Lazy import :mod:`rlcompleter` in :mod:`pdb` to avoid deadlock in subprocess.
diff --git a/Misc/stable_abi.toml b/Misc/stable_abi.toml
index d651e0fac111b1..4a03cc76f5e1e9 100644
--- a/Misc/stable_abi.toml
+++ b/Misc/stable_abi.toml
@@ -1600,6 +1600,7 @@
     added = '3.2'
 [function.PyWeakref_GetObject]
     added = '3.2'
+    abi_only = true
 [function.PyWeakref_NewProxy]
     added = '3.2'
 [function.PyWeakref_NewRef]
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index a5c4604056ab4e..508ef55511e49d 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -2206,9 +2206,8 @@ test_macros(PyObject *self, PyObject *Py_UNUSED(args))
 static PyObject *
 test_weakref_capi(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
 {
-    // Ignore PyWeakref_GetObject() deprecation, we test it on purpose
-    _Py_COMP_DIAG_PUSH
-    _Py_COMP_DIAG_IGNORE_DEPR_DECLS
+    // Get the function (removed in 3.15) from the stable ABI.
+    PyAPI_FUNC(PyObject *) PyWeakref_GetObject(PyObject *);
 
     // Create a new heap type, create an instance of this type, and delete the
     // type. This object supports weak references.
@@ -2249,19 +2248,12 @@ test_weakref_capi(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
     ref = PyWeakref_GetObject(weakref);  // borrowed ref
     assert(ref == obj);
 
-    // test PyWeakref_GET_OBJECT(), reference is alive
-    ref = PyWeakref_GET_OBJECT(weakref);  // borrowed ref
-    assert(ref == obj);
-
     // delete the referenced object: clear the weakref
     assert(Py_REFCNT(obj) == 1);
     Py_DECREF(obj);
 
     assert(PyWeakref_IsDead(weakref));
 
-    // test PyWeakref_GET_OBJECT(), reference is dead
-    assert(PyWeakref_GET_OBJECT(weakref) == Py_None);
-
     // test PyWeakref_GetRef(), reference is dead
     ref = UNINITIALIZED_PTR;
     assert(PyWeakref_GetRef(weakref, &ref) == 0);
@@ -2312,8 +2304,6 @@ test_weakref_capi(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
     Py_DECREF(weakref);
 
     Py_RETURN_NONE;
-
-    _Py_COMP_DIAG_POP
 }
 
 struct simpletracer_data {
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index bd4c4ac9b3475a..61fa3ddad0bfd8 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -964,7 +964,8 @@ PyWeakref_GetRef(PyObject *ref, PyObject **pobj)
 }
 
 
-PyObject *
+/* removed in 3.15, but kept for stable ABI compatibility */
+PyAPI_FUNC(PyObject *)
 PyWeakref_GetObject(PyObject *ref)
 {
     if (ref == NULL || !PyWeakref_Check(ref)) {
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 9b993188fb73c7..f9f14322df0a5e 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -2940,9 +2940,10 @@ dummy_func(
         };
 
         tier1 op(_SPECIALIZE_JUMP_BACKWARD, (--)) {
-        #if ENABLE_SPECIALIZATION
+        #if ENABLE_SPECIALIZATION_FT
             if (this_instr->op.code == JUMP_BACKWARD) {
-                this_instr->op.code = tstate->interp->jit ? JUMP_BACKWARD_JIT : JUMP_BACKWARD_NO_JIT;
+                uint8_t desired = tstate->interp->jit ? JUMP_BACKWARD_JIT : JUMP_BACKWARD_NO_JIT;
+                FT_ATOMIC_STORE_UINT8_RELAXED(this_instr->op.code, desired);
                 // Need to re-dispatch so the warmup counter isn't off by one:
                 next_instr = this_instr;
                 DISPATCH_SAME_OPARG();
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index e33d15f2e51e16..79328a7b725613 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -7589,9 +7589,10 @@
             /* Skip 1 cache entry */
             // _SPECIALIZE_JUMP_BACKWARD
             {
-                #if ENABLE_SPECIALIZATION
+                #if ENABLE_SPECIALIZATION_FT
                 if (this_instr->op.code == JUMP_BACKWARD) {
-                    this_instr->op.code = tstate->interp->jit ? JUMP_BACKWARD_JIT : JUMP_BACKWARD_NO_JIT;
+                    uint8_t desired = tstate->interp->jit ? JUMP_BACKWARD_JIT : JUMP_BACKWARD_NO_JIT;
+                    FT_ATOMIC_STORE_UINT8_RELAXED(this_instr->op.code, desired);
                     next_instr = this_instr;
                     DISPATCH_SAME_OPARG();
                 }
diff --git a/Python/optimizer.c b/Python/optimizer.c
index 53f1500f3989a4..7b76cddeabff44 100644
--- a/Python/optimizer.c
+++ b/Python/optimizer.c
@@ -119,6 +119,7 @@ _PyOptimizer_Optimize(
     PyInterpreterState *interp = _PyInterpreterState_GET();
     assert(interp->jit);
     assert(!interp->compiling);
+#ifndef Py_GIL_DISABLED
     interp->compiling = true;
     // The first executor in a chain and the MAX_CHAIN_DEPTH'th executor *must*
     // make progress in order to avoid infinite loops or excessively-long
@@ -160,6 +161,9 @@ _PyOptimizer_Optimize(
     assert((*executor_ptr)->vm_data.valid);
     interp->compiling = false;
     return 1;
+#else
+    return 0;
+#endif
 }
 
 static _PyExecutorObject *
diff --git a/configure b/configure
index cd8f2f19c0b92c..7624cbf0d2ae3d 100755
--- a/configure
+++ b/configure
@@ -10891,7 +10891,8 @@ printf "%s\n" "$tier2_flags $jit_flags" >&6; }
 if test "$disable_gil" = "yes" -a "$enable_experimental_jit" != "no"; then
   # GH-133171: This configuration builds the JIT but never actually uses it,
   # which is surprising (and strictly worse than not building it at all):
-  as_fn_error $? "--enable-experimental-jit cannot be used with --disable-gil." "$LINENO" 5
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: --enable-experimental-jit does not work correctly with --disable-gil." >&5
+printf "%s\n" "$as_me: WARNING: --enable-experimental-jit does not work correctly with --disable-gil." >&2;}
 fi
 
 case "$ac_cv_cc_name" in
diff --git a/configure.ac b/configure.ac
index 8312dc55084333..7a7e32d42945b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2799,7 +2799,7 @@ AC_MSG_RESULT([$tier2_flags $jit_flags])
 if test "$disable_gil" = "yes" -a "$enable_experimental_jit" != "no"; then
   # GH-133171: This configuration builds the JIT but never actually uses it,
   # which is surprising (and strictly worse than not building it at all):
-  AC_MSG_ERROR([--enable-experimental-jit cannot be used with --disable-gil.])
+  AC_MSG_WARN([--enable-experimental-jit does not work correctly with --disable-gil.])
 fi
 
 case "$ac_cv_cc_name" in