narcisgarcia

Take care to not export database with “–compatible=mysql40” option. It causes the ID fields to have not “auto_increment” attribute.

When posts or comments tables don’t have “auto_increment” option on their ID fields, WordPress produces registers with ID 0 because WordPress assumes that the ID is autogenerated by MySQL.

It can also affect to uploaded files.

With a WordPress 2.1.2 , an user tried to upload a file.doc and then it appeared the same error message (duplicate entry 2500).

I have explored the last register in “wp_comments” table, ans I’ve seen in the “comment_ID” field a “2499” value.
Then I edited that value to set it a “2501” value.

People can now add comments again without problem.