Convert error during import from Omeka classic to OmekaS

I’am building a new omekaS site from an existing Omeka classic one (with Omeka classic Importer).
Almost everything is ok . Some media are missing (jpf files for example).
I have some logs :

Does anyone have any idea where I can look?
During conversion the images are deleted from /tmp, so it’s hard to find any trace of the images or pdf that caused the problem.
Thank you for your help.