When I moved my customer WordPress website from another platform, after the successful files and database transfer. I’ve got this error.
“Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0”
To fix this issue.
I disabled all plugins one by one, refresh the screen to figure out the what causing it. One of the plugin did it so I disable and re-activated to fix the fatal error.
RESOLVED!