We have been using SVN for the past year now and when we migrated to an online server we started getting this error:

Commit: Commit failed (details follow): File or directory 'x.php' is out of date; 
try updating resource out of date; 
try updating CHECKOUT of '/!svn/ver/491/x.php': 409 Conflict (http://svn.example.com)

We are currently using SmartSVN 6.5 and we have also tested with RapidSVN & Syncro (but we can't use tortoise as we have a lot of Ubunutu users)

at the begining I though this How do you fix an SVN 409 Conflict Error would help, but it didn't we are still facing the same error and it's even more absurd now.

the main problem is that after you get the error, you can't shake it of. Updating doesn't solve, reverting doesn't solve. You are just stuck with the error. The only thing that could work is removing the file from SVN and adding your version but that would be against why we are using SVN in the first place

This is our apache config (and yes autoversioning is ON)

<Location />
  DAV svn
  SVNPath /home/example/svn
  SVNAutoversioning on
  AuthType Basic
  AuthName "Access Restricted"
  AuthUserFile /home/example/svn-auth-file
  Require valid-user
</Location>

<Directory />
  <Files ~ "^\.ht">
        Order allow,deny
        Allow from all
        Satisfy All
  </Files>

  <Files ~ "^error_log">
        Order allow,deny
        Allow from all
        Satisfy All
  </Files>
</Directory>

And here are some observation:

1. We don't receive conflicts anymore, we just get this 409 conflict
2. you can somehow avoid the error if you always update before committing
3. When committing a modified file + a newly added file, you get the error. As if the added file incremented the version by one and then you are committing another file with a older version.

Please advise, we are about to go insane