I installed SNAP on Ubuntu 16.04 and I had the error bellow at startup.
I tried the version 6 and 5. I got the same error.
My uname -a:
Linux HP1710W004-Ubuntu 4.13.0-39-generic #44~16.04.1-Ubuntu SMP Thu Apr 5 16:43:10 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux