After some additional troubleshooting I've discovered that when I go to the Properties > Custom Attributes tab for the page to which I am attempting to add a sub-page I see:

Fatal error: Call to a member function getAttributeKeyID() on a non-object in /home/aurorara/public_html/concrete/elements/collection_metadata_fields.php on line 18

When I go to any other pages and attempt to add sub pages they work fine.

When I go to line 18 mentioned in the error above it reads:

$usedKeys[] = $ak->getAttributeKeyID();

The same is true for line 227 of the file mentioned in the original error report of this thread.

If any additional information would be useful I'd be happy to gather it.

Any help you could provide would be much appreciated.

Thank you

have you made any changes directly in the database to anything at all - or have you recently uninstalled anything - plugin/theme, or maybe switched themes?

Thank you for your post.

The hosting service had some trouble with a data overflow in their tmp directory recently which produced an error when attempting to access my site, but went away once they had fixed that. They insist that would not corrupt data on my site.

The only other activity on my domain recently was to install phpList in preparation for operating a mailing list.

Hope this helps. Thank you