The workaround posted on here doesn't seem to work for me, I'm still getting the following error:
/opt/PixInsight/bin/PixInsight: /opt/PixInsight/bin/lib/libz.so.1: version `ZLIB_1.2.9' not found (required by /usr/lib/x86_64-linux-gnu/libpng16.so.16)
/opt/PixInsight/bin/PixInsight: /opt/PixInsight/bin/lib/libstdc++.so.6: version `CXXABI_1.3.11' not found (required by /usr/lib/x86_64-linux-gnu/libmirclient.so.9)
I have the newest version of Ubuntu, and installed the latest version of PixInsight, had this issue with old version and thought uninstalling and installing the newest release would fix the problem, but no such luck.
Edit: I found a fix for this that worked for me
cd /opt/PixInsight/bin/lib
sudo mv libz.so.1 libz.so.1.bak
sudo mv libstdc++.so.6 libstdc++.so.6.bak