Ubuntu 25.10 is a new worker, so this is probably a configuration issue. I could mail helpdesk directly, but I'm not sure what exactly needs to be changed.

Confirmed it reproduces on the same worker and does not seem to happen on any other worker.

SDK testing environment: x86-64-v3-poky-linux.bat
Traceback (most recent call last):
  File "/srv/pokybuild/yocto-worker/meta-mingw/build/layers/openembedded-core/meta/lib/oeqa/core/case.py", line 54, in _oeSetUp
    self.setUpMethod()
    ~~~~~~~~~~~~~~~~^^
  File "/srv/pokybuild/yocto-worker/meta-mingw/build/meta-mingw/lib/oeqa/sdkmingw/cases/binutils.py", line 25, in setUp
    self._run('%CC% -c -g test.c -o test.o')
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/srv/pokybuild/yocto-worker/meta-mingw/build/meta-mingw/lib/oeqa/sdkmingw/case.py", line 67, in _run
    return subprocess.check_output(command, env=self.tc.get_wine_env(),
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            stderr=subprocess.STDOUT, universal_newlines=True, cwd=self.test_dir)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/subprocess.py", line 472, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
           ~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
               **kwargs).stdout
               ^^^^^^^^^
  File "/usr/lib/python3.13/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
oeqa.utils.subprocesstweak.OETestCalledProcessError: Command '['wine', 'cmd', '/c', 'W:\\testimage-sdk\\environment-setup-x86-64-v3-poky-linux.bat', '>', 'NUL', '&&', '%CC%', '-c', '-g', 'test.c', '-o', 'test.o']' returned non-zero exit status 1.
Standard Output: test.c:1:10: fatal error: stdio.h: No such file or directory
    1 | #include <stdio.h>
      |          ^~~~~~~~~
compilation terminated.