Pmwiki is pretty robust and can figure out and fix on its own lots of errors and config omissions.

However, if the wiki suddenly stops responding, try deleting the lock file (wiki.d/.flock)

• If you don't know how, open the ftp program you use to upload script changes, go to the wiki.d directory (one level below pmwiki.php), select the file called .flock and press Delete (or right-click on it and choose Delete). Make sure you select ONLY the .flock file.

When the error "Cannot modify header information -- headers already sent" is the first error message to appear, it almost always means that there are extra spaces or blank lines outside of the <?php ... ?> in one of the .php scripts being used.

• To fix this, simply check the php files reported with the error, or pmwiki.php or any php files included in any local/ php file, and make sure they start with
 <?php if (!defined('Pm Wiki')) exit();

and they end with
 ?>

and no other lines after that.

If you set any passwords, and the wiki starts asking for a password for each page read or twice per edit, it usually indicates a problem with

• cookies -- make sure your browser is set to handle cookies, or
• session handling somewhere -- i.e., PHP isn't able to save/restore session data properly.

Check (using phpinfo() or ?action=diag) whether sessions are enabled in your version of php, then check where the session.save_path is set to, and check the permissions on this directory and that session files are appearing there properly.

You might also try adding

   session_save_path('/path/to/somewhere/writable');


to your local/config.php and see if that fixes things.

When editing pages, it is possible to continuously get the revision edit form (i.e. after pressing Save, the edit page comes back with

 <<<<<<<
stuff I just added plus older stuff
=======
older stuff
>>>>>>>


... placed around stuff you had just edited). It's a rare bug, but when it happens, a tested cure is to dowload the page from wiki.d using your normal ftp client, then immediately upload it.