An exception occurred: AttributeError module 'sys' has no attribute 'real_prefix' #923

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1. github-actions

   added

   triage-neededNeeds assignment to the proper sub-teamNeeds assignment to the proper sub-team

   on Jan 9, 2026
2. rchiodo commented on Jan 9, 2026

   

   Rich Chiodo (rchiodo)

   on Jan 9, 2026

   Contributor

   More actions

   Something is changing 'eval' to not work. This code works fine for me. You can try sticking this in the file you're debugging and see what happens:

   import os
   import sys
   import inspect
   
   def force_str(s, encoding, errors="strict"):
       """Converts s to str, using the provided encoding. If s is already str,
       it is returned as is.
       """
       return s.decode(encoding, errors) if isinstance(s, bytes) else str(s)
   
   def nameof(obj, quote=False):
       """Returns the most descriptive name of a Python module, class, or function,
       as a Unicode string
   
       If quote=True, name is quoted with repr().
   
       Best-effort, but guaranteed to not fail - always returns something.
       """
   
       try:
           name = obj.__qualname__
       except Exception:
           try:
               name = obj.__name__
           except Exception:
               # Fall back to raw repr(), and skip quoting.
               try:
                   name = repr(obj)
               except Exception:
                   return "<unknown>"
               else:
                   quote = False
   
       if quote:
           try:
               name = repr(name)
           except Exception:
               pass
   
       return force_str(name, "utf-8", "replace")
   
   def srcnameof(obj):
       """Returns the most descriptive name of a Python module, class, or function,
       including source information (filename and linenumber), if available.
   
       Best-effort, but guaranteed to not fail - always returns something.
       """
   
       name = nameof(obj, quote=True)
   
       # Get the source information if possible.
       try:
           src_file = inspect.getsourcefile(obj)
       except Exception:
           pass
       else:
           name += f" (file {src_file!r}"
           try:
               _, src_lineno = inspect.getsourcelines(obj)
           except Exception:
               pass
           else:
               name += f", line {src_lineno}"
           name += ")"
   
       return name
   
   def evaluate(code, path=__file__, mode="eval"):
       # Setting file path here to avoid breaking here if users have set
       # "break on exception raised" setting. This code can potentially run
       # in user process and is indistinguishable if the path is not set.
       # We use the path internally to skip exception inside the debugger.
       expr = compile(code, path, "eval")
       return eval(expr, {}, sys.modules)
   
   def swallow_exception(msg, *args, level="error", **kwargs):
       print(msg.format(*args, **kwargs))
   
   def get_environment_description(header):
       import sysconfig
       import site  # noqa
   
       result = [header, "\n\n"]
   
       def report(s, *args, **kwargs):
           result.append(s.format(*args, **kwargs))
   
       def report_paths(get_paths, label=None):
           prefix = f"    {label or get_paths}: "
   
           expr = None
           if not callable(get_paths):
               expr = get_paths
               get_paths = lambda: evaluate(expr)
           try:
               paths = get_paths()
           except AttributeError:
               report("{0}<missing>\n", prefix)
               return
           except Exception:  # pragma: no cover
               swallow_exception(
                   "Error evaluating {0}",
                   repr(expr) if expr else srcnameof(get_paths),
                   level="info",
               )
               return
   
           if not isinstance(paths, (list, tuple)):
               paths = [paths]
   
           for p in sorted(paths):
               report("{0}{1}", prefix, p)
               if p is not None:
                   rp = os.path.realpath(p)
                   if p != rp:
                       report("({0})", rp)
               report("\n")
   
               prefix = " " * len(prefix)
   
       report("System paths:\n")
       report_paths("sys.executable")
       report_paths("sys.prefix")
       report_paths("sys.base_prefix")
       report_paths("sys.real_prefix")
       report_paths("site.getsitepackages()")
       report_paths("site.getusersitepackages()")
   
       site_packages = [
           p
           for p in sys.path
           if os.path.exists(p) and os.path.basename(p) == "site-packages"
       ]
       report_paths(lambda: site_packages, "sys.path (site-packages)")
   
       for name in sysconfig.get_path_names():
           expr = "sysconfig.get_path({0!r})".format(name)
           report_paths(expr)
   
       report_paths("os.__file__")
       report_paths("threading.__file__")
       report_paths("debugpy.__file__")
       report("\n")
   
       importlib_metadata = None
       try:
           import importlib_metadata
       except ImportError:  # pragma: no cover
           try:
               from importlib import metadata as importlib_metadata
           except ImportError:
               pass
       if importlib_metadata is None:  # pragma: no cover
           report("Cannot enumerate installed packages - missing importlib_metadata.")
       else:
           report("Installed packages:\n")
           try:
               for pkg in importlib_metadata.distributions():
                   report("    {0}=={1}\n", pkg.name, pkg.version)
           except Exception:  # pragma: no cover
               swallow_exception(
                   "Error while enumerating installed packages.", level="info"
               )
   
       return "".join(result).rstrip("\n")
   
   print(get_environment_description("Environment description:"))

   That code is identical to what debugpy is running and I get no such exception. The eval is failing for you for some reason.
3. Rich Chiodo (rchiodo)

   closed this as completedon Jan 9, 2026
4. Charron-Lin commented on Jan 15, 2026

   

   Charron (Charron-Lin)

   on Jan 15, 2026

   More actions

   I installed Python 3.10.11, and debugging also reports this error. It started recently.
   Have you solved this problem?