Thanks Trevor. I don't seem to have a directory moodle/theme/myoldertheme to put version.php into. I tried creating a folder named myoldertheme but it just made things worse. Clearing cache didn't help either.
Here's the error:
Debug info:
Error code: detectedmisplacedplugin
Error code: detectedmisplacedplugin
Stack trace:
Checking on Moodle Tracker I found this:- line 454 of /lib/upgradelib.php: plugin_misplaced_exception thrown
- line 1630 of /lib/upgradelib.php: call to upgrade_plugins()
- line 433 of /admin/index.php: call to upgrade_noncore()
Let me guess, you arrived here after trying to install a new theme? If so then check that the version.php of the theme in question, and make sure that it is completed correctly, especially this line...
$plugin->component = 'theme_yourthemename'; // Full name of the plugin (used for diagnostics)
...where 'yourthemename' is the correct spelling of the theme you are trying to install.
Thing is I'm not trying to install a new theme, this was just an upgrade.Do you have any ideas?