Admin 404 error in WP 4.4 for some Sub-directory Installations

[joshuadnelson]

In some sub-direction installations of WP, after upgrading to 4.4 the admin results in a 404 error. We've reproduced the issue, but have been unable to diagnose the cause: ​https://wordpress.org/support/topic/help-cannot-login-or-access-dashboard-after-wp-update-to-44.

I have a few other sites in sub-directories without issues, however the site in question with the issue has gone through all the typical methods of solving a 404 issue without avail. Others on the support ticket linked above have reported the same issue.

[joshuadnelson]

May not be limited to subdirectories: ​https://wordpress.org/support/topic/help-cannot-login-or-access-dashboard-after-wp-update-to-44/page/2?replies=34#post-7770876

[jorbin]

@dd32 - I saw on the comment thread you were getting in contact with one of the affected people. Anything to report from that conversation?

From the sounds of the support forum, this relates to file permissions but hasn't been root caused.

[dd32]

I've been in touch with two affected users.
This doesn't appear to be a 4.4 issue.

In one case there was a bad cdn + security plugin blocking access.
In another (The reporter of this ticket) file permissions were wrong, seemingly caused by some change on the server.

Couldn't see any way to blame WordPress unfortunately.

[iforceman]

I'm getting a 404 error when I click on either Updates or Plugins.

Is this similar to what is being reported? Please advise what to do.

[dd32]

@iforceman It's likely a hosting misconfiguration, you should check the permissions of the files on your account. I'll send you a follow up email shortly.