ubuntu20.04 installs ns3.33 and reports an error task in ‘ns3-core‘ failed with exit status 1 reason

The reason is very simple ns3-3.33 is relatively old
When installing dependencies according to the official tutorial
The gcc version will be given by default if you are ubuntu20.04 You install gcc11
However, too high a gcc version can also cause problems
so you can just downgrade gcc to version 9 (you can install multiple gccs by searching for the command yourself) Then set the priority)
and the python version is also reduced to 3.7, otherwise the error will still be reported! (Different errors)
So there are two solutions:
The higher version of gcc and python corresponds to the higher version of ns3
The lower version gcc and python correspond to the lower version ns3