Question:

Today, when installing the software package, I found that an error occurred when executing the add apt repository command, and the software source could not be added

Traceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 191, in <module>
    if not sp.add_source_from_shortcut(shortcut, options.enable_source):
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 777, in add_source_from_shortcut
    if worker.isAlive():
AttributeError: 'Thread' object has no attribute 'isAlive'

reason:

The file softwareproperties.py refers to “isalive”. The python version installed on the computer is 3.9.2. This method is no longer supported in 3.9.

Solution:

Modify the “/ usr/lib/python3/dist packages/softwareproperties/softwareproperties. Py” file, and change the “isalive” in line 777 to “is_live”.