crash when uploading picture files

Dear all,

When importing a picture file (jpg, png) in attached file, we get this crash error :
Hibernate operation: Could not execute JDBC batch update; SQL []; Cannot add or update a child row: a foreign key constraint fails (`confluence`.`IMAGEDETAILS`, CONSTRAINT `FKA768048734A4917E` FOREIGN KEY (`ATTACHMENTID`) REFERENCES `ATTACHMENTS_BACKUP` (`ATTACHMENTID`)); nested exception is java.sql.BatchUpdateException: Cannot add or update a child row: a foreign key constraint fails (`confluence`.`IMAGEDETAILS`, CONSTRAINT `FKA768048734A4917E` FOREIGN KEY (`ATTACHMENTID`) REFERENCES `ATTACHMENTS_BACKUP` (`ATTACHMENTID`))

It works fine with other file types (xlsx, docx, pdf, ...).
We are running Confluence 5.8.8, upgraded 6 months ago.

Many thanks for your help

Thierry Mignard - IT Manager Studyrama