I saw several papges about this issue, such as:

https://inkscape.org/forums/beyond/interpolate-pattern-along-path-bug/?c=67084#c67084

https://inkscape.org/forums/questions/error-message/

https://inkscape.org/forums/questions/interpolate-extensions/

https://gitlab.com/inkscape/extensions/-/issues/316

https://gitlab.com/inkscape/inbox/-/issues/3098

and inkscape always reports: Inkscape has received additional data from the script executed. The script did not return an error, but this may indicate the results will not be as expected

I googled around and found no solution, so I share the solution here. This kind of issues always include this line of code: 

self._handle = _dlopen(self._name, mode)

It is python code bundled with inkscape, and the solution is very simple, that is find the file first and not passing 'mode' parameter here(delete parameter mode).

Take https://inkscape.org/forums/beyond/interpolate-pattern-along-path-bug/?c=67084#c67084 for example.
First, open this file "C:\Program Files\Inkscape\lib\python3.8\ctypes\__init__.py" with an editor.

Second, locate to line 373 and change it to 
self._handle = _dlopen(self._name)

Third, save and exit.

This bug seems to happen in win7 sp1 only, so upgrading the OS can also work, but if you have some reason to insist on win 7, this slution may fit you.