Cannot debug apps (sometimes)

I try to start the debugger for an application and got:

{{LLDB STDERR UNEXPECTED: "Traceback (most recent call last):\n File \"<input>\", line 1, in <module>\n File \"/usr/local/Cellar/python@2/2.7.14_3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/copy.py\", line 52, in <module>\n import weakref\n File \"/usr/local/Cellar/python@2/2.7.14_3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/weakref.py\", line 14, in <module>\n from _weakref import (\nImportError: cannot import name _remove_dead_weakref\n"
SOFT ASSERT: "isRunning()" in file /work/build/qt-creator/src/plugins/projectexplorer/runconfiguration.cpp, line 1145
SOFT ASSERT: "runTool" in file /work/build/qt-creator/src/plugins/debugger/debuggerplugin.cpp, line 2577
SOFT ASSERT: "runTool()" in file /work/build/qt-creator/src/plugins/debugger/debuggerengine.cpp, line 1342
SOFT ASSERT: "isRunning()" in file /work/build/qt-creator/src/plugins/projectexplorer/runconfiguration.cpp, line 1145
SOFT ASSERT: "isRunning()" in file /work/build/qt-creator/src/plugins/projectexplorer/runconfiguration.cpp, line 1145}}

So I updated my python:
LLDB STDERR UNEXPECTED: "Traceback (most recent call last):\n File \"<input>\", line 1, in <module>\n File \"/usr/local/Cellar/python@2/2.7.15/Frameworks/Python.framework/Versions/2.7/lib/python2.7/copy.py\", line 52, in <module>\n import weakref\n File \"/usr/local/Cellar/python@2/2.7.15/Frameworks/Python.framework/Versions/2.7/lib/python2.7/weakref.py\", line 14, in <module>\n from _weakref import (\nImportError: cannot import name _remove_dead_weakref\n"

But I can import weakref manually fine:

{{Python 2.7.15 (default, May 17 2018, 12:45:18)
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from _weakref import _remove_dead_weakref
>>> import weakref
>>>}}