CharlesInColorado

I began suddenly having problems with the BackUpWordPress plugin recently–error message popping up instead of my website & couldn’t get into my WP dashboard. I logged into cPanel and updated my PHP, did some stuff on my WP dashboard, logged out, and then got the error message again! Somehow, my PHP had reverted to the previous version. *sigh*.
Couple of rounds of this and I got in touch with my host’s tech support…here’s what he said:

Ahh, I found the culprit. There’s a file in public_html/wp-includes called nav-menu.php. Looks like there are a couple of lines of code forcing the .htaccess to reset to 0444 permissions. Looks like you’re on WordPress 4.2.4, upgrading to WordPress 4.3 will remove the existing nav-menu.php file and replace it with a stock version, so you should be able to edit the .htaccess again.

Apparently, one of the several websites I have there was on an older version of WP. Didn’t know which that might be, so I asked him to replace that file for me and he did; here was his followup:

Yeah, no problem! I’m glad we could narrow that down. A lot of customers have actually had the same thing implanted to the nav-menu.php, actually. Normally that’d mean a plugin or a theme has a vulnerability allowing the code to be inserted, but I honestly have not found a common plugin that everybody has when I see this. I wish I had more info as to WHY that happened, but I’m glad it’s an easy fix.

If you’re having trouble with this even after you “fix” the issue, double check that your PHP stays updated–this is apparently a fairly common problem.