MyBB Community Forums

So I'm having issues with my forum templates, keep trying to edit files and for some reason I get an forbidden page after saving changes.
Happened to me twice and had to edit the template manually and re-upload it. But I've already made changes to the template on some parts that allowed me to save and on the forums.

It's annoying me like crazy, how do I solve this? Thank you
https://imgur.com/XqVXb0l

looks like mod_security (or suhosin) is affecting.
please contact your web host for disabling such security or
ask them to add required white rules by analyzing error logs.

(2019-04-05, 04:11 PM).m. Wrote: [ -> ]looks like mod_security (or suhosin) is affecting.
please contact your web host for disabling such security or
ask them to add required white rules by analyzing error logs.

Thank you