How to repair a serialized string which has been corrupted by an incorrect byte count length?

Question

I am using Hotaru CMS with the Image Upload plugin, I get this error if I try to attach an image to a post, otherwise there is no error:

unserialize()

Answer 1

Another reason of this problem can be column type of "payload" sessions table. If you have huge data on session, a text column wouldn't be enough. You will need MEDIUMTEXT or even LONGTEXT.