"Call to undefined function shell_exec()" at /site-archive/pfecvidmanagepfcomuk-1729239807/app/modules/contrib/advagg/advagg_ext_minify/advagg_ext_minify.install line 20

fatal errors while running Opigno on them.

"Call to undefined function shell_exec()" at modules/contrib/advagg/advagg_ext_minify/advagg_ext_minify.install line 20

Proposed resolution

Check if shell_exec is callable and in the enabled functions list