Categories corrupted

Ideally, restore your DB from a backup made before the categories became corrupted. The problem is you’ll lose anything changed after the backup was made.

How did they become corrupted? You need to ensure it doesn’t happen again. If a lot of data is involved, repairing it again and again may not be trivial. How many category terms are involved? And how many posts/products need the problem terms assigned? Correcting a large amount of data will be time consuming.

A possible solution is to correct the DB directly with the phpMyAdmin app. It’s easier to remove the data than to attempt to patch it. Once removed and you know it will not happen again, you can re-enter the terms and assign them to posts/products again.

There are 3 or 4 tables involved with taxonomy terms. This requires understanding how they interrelate in order to correctly remove the offending terms without further corrupting the data. The understanding can be gained by studying the tables in phpMyAdmin. Be sure to make a backup of all affected tables before making any changes. It’s not difficult to make things worse instead of better even if you know what you’re doing. This is not a task to take lightly. Consider carefully if this is something you want to take on.

I’ve looked at the database and discovered that all the corrupted categories have a term_id of 0.This is the case under terms, term_taxonomies and term_relationships. Changing the term id of one of the corrupted terms causes them to no longer show on the list of categories in wordpress’s categories section.
I do not know how the database became corrupted, this was a pre-existing site I took over management of for a client.The first corrupted categories are related to woocommerce, so it looks like that is when the issue began.
Unfortunately because it looks like the problem began some time ago, a database restore will not solve the issue.
It looks like a rebuilding of the affected database sections will need to be done to resolve it.

Wow, that’s strange. Hopefully it was a one time occurrence and some plugin is not actively corrupting things. If the problem terms all have IDs of 0, at least it’ll be easy to construct queries to remove the data. The difficulty would be in re-assigning the terms to the objects to which they belong.

If the object to term relationship is still apparent despite 0 ID, I suppose it’s conceivable to reconstruct the data using new, unused ID values. The next available ID in the terms table can be determined from the auto increment field under table options (operations tab). Increment the field value for every ID you use. If there are only a few terms to repair this is feasible to do manually. If it’s a large number, maybe the logic to repair the data can be captured in a script that does the repairs.