White page after upgrade to PHP 7.1

[wageral]

I'm running two MyBB forums. Both with the latest version 1.8.19.
After upgrading from PHP 5.6 to PHP 7.1 one of the forums works fine (except some small issues regarding plugins).
The other forum gives nothing but a white (blanc) page.

I checked both the settings.php and config.php but cannot find anything strange.
This second forum has the same plugins as de first one, so it seems it's not a plugin-related issue.

Any ideas what's going wrong?

[vk_knight]

I tried in a free server once faced the same problem. I still don't know why. Can I ask which plugins you have installed?

I urge the mybb community to fix this php problem first rather than giving a version update.

[wageral]

After checking the error-log I found the solution:
The 'Undo-delete'-plugin caused this problem.
https://mods.mybb.com/view/undo-delete 
After deleting this plugin everything works fine again.

[0xB9]

It is known that some plugins have issues running on php7, however MyBB itself should run fine on php7 from what I'm aware of and my experience.

[vk_knight]

After checking the error-log I found the solution:
The 'Undo-delete'-plugin caused this problem.
https://mods.mybb.com/view/undo-delete 
After deleting this plugin everything works fine again.

Glad that you got it resolved.