Hello, i got an 404 and 401 error after changing "WHMCS SSL System URL" in Admin area, General Settings.
This "Not Found" error appeared only in Admin area so i was unable to change it back.

Not sure what is the cause?

But what fixed the issue is this:

to go to mysql manager (PhpMyAdmin in my case) and find table "tblconfiguration", here is an line "SystemSSLURL" which contained my URL.

My aim was to remove it to be blank again.

So i exported whole "tblconfiguration" table to a file. Then opened that file and found "SystemSSLURL"

i did replacement in code:

('SystemSSLURL', 'http://mydomain/'),

to become:

('SystemSSLURL', ''),

then coppied all file contents, then delete "tblconfiguration" table making my WHMCS non working and then click "SQL" tab in PHPMyAdmin and pasted the content frm clipboard. And execute.

So the table "tblconfiguration" was created again, but without "SystemSSLURL" set.

It was fixed