File not uploading on File manager

after trying to upload file in Directadmin File Manager in reseller account, I get this error:

"Unknown error
Unable to open /home/tmp/8acwf7g6048w8okgkc0w84sc4uGWBeN for reading

Waing: Saved filesize is less than uploaded filesize. Check quotas.
Waing: Quota limit reached. File(s) may be empty."

Disk space is not empty and quota was nos reached.

Maybe someone has an idea?