Background

An attachment and its container could be related to different spaces.
It could happen if the page is moved to another space.
As a result, the import process of such spaces could fail with "could not execute statement".

Expected behaviour

Attachments and their containers must be related to the same space.

Workaround

https://confluence.atlassian.com/confkb/importing-a-space-fails-with-could-not-execute-statement-error-in-confluence-server-949242294.html

Additional information

To test if database is affected by bug, this script could be run:

SELECT COUNT(*)
FROM CONTENT
JOIN CONTENT xpage ON CONTENT.PAGEID = xpage.CONTENTID
WHERE CONTENT.SPACEID != xpage.SPACEID
AND CONTENT.CONTENTTYPE = 'ATTACHMENT';

If it returns non-zero value, database is affected by this bug.