WordPress MU

Hi all, I have a Wordpress MU that was functional and working great on 2.5 (on a Linux server). I tried to upgrade it, as the site has expanded quite a bit and am now getting the blank screen error. Checked all the logs (including PHP with my webhost) and no errors are being reported. The backend admin area is working fine and I have gone through the upgrade. Also checked out the permissions and all that stuff, but still no dice.

I deleted all my plugins and tried a number of themes - the interesting thing is that even with the new theme previews, I'm getting a blank screen preview.

I'm wondering if something could have been problematic in the database with an old plugin or something? I've searched the forums comprehensively and have still not been able to find a solution to the problem.

Any ideas or should I think about restoring a backup?

If you've a blank screen then you should be getting something in the php error logs.

You would think so, but I've had support check and double check. No PHP problems... :(

So its a totally blank page when you try to look at the blog? If you look at the source of the page is it empty too or is there some html there?

The source is empty as well.

I have also double checked the settings to make sure it's directed to the correct directory, blog, etc. and it all seems to be correct. That was my first guess, not sure why else it would do that...

Remove all the plugins and all the mu-plugins. Make sure the theme selected on the main blog is the default one (just to eliminate everything).

Then add the plugins back one by one.

I did remove all the plugins, didn't think to try one by one. Could that potentially correct any database weirdness?

no, not really. might have to go peek if the db is indeed got weird info in it.

many plugins, even when you deactivate them, fail to remove their info from the db.

steve - it's definitely the usual WSOD. something's bombing.

take out all the mu-plugins as well.

Definitely cleared all plugin folders - I've even backed up all the themes if I need to remove those.

I'll start looking through the DB and see what I can figure out. I'll also search the forums, there's likely been a post about what tables are the only ones that are necessary (unless anyone knows it quickly offhand).

Remove wp-config (back it up/rename it to wp-config-old.php or so), run the installer again, like you are setting up things from scratch.

Worked for me, still do not knwo why regular upgrade did not work, might be slight changes in the wp-config between versions.
Good luck.

If you remove the themes, you'll definitely get a WSOD. (ask me how I know :D )

DB structure - http://codex.wordpress.org/WPMU_Database_Description

I will try the "fresh install" method. To keep the site running, I opted to reinstall my backup of 2.6 just so we didn't lose integrity among members. I may go ahead and take another backup (that's still working) and try to do the "fresh install method" mentioned by Bike.

Thank you guys for all the help! Will report on progress ASAP.

If you remove the themes, you'll definitely get a WSOD. (ask me how I know :D )

OK, how do you know and why is this so?
Thanks

I know because I did it by accident. :D

And why does this do this? The selected them is stored in the database. remove the theme, and it can't find those files, because they no longer exist. So it throws an error.

Pretty logical actually.