fwconsole returns nothing and GUI returns blank page but no error message

Hello,
We have a Free PBX (v15) which has been working very well for two years without problems. Suddenly, for a week, the graphical interface displays a blank page and the fwconsole command returns nothing, neither positive message nor error.

I scoured the server for logs with errors, nothing.

After several hours of trying to find the solution, I wonder if anyone else here has experienced this and what was the solution?

Thank you beforehand,