Nextcloud Desktop App PROBLEM Sync file .PSD

Hello, I am writing to you about a problem that I am having in the synchronization of the cloud with my shared folders on the PC, every time it crashes with this Error: 503 Service Unavailable a GET https // / remote.php / dav / files / raceit / 1) RaceIT - Championships / Partners Logos / 3DRAP / 3DRAP.psd

This error blocks synchronization and the ability to save content on my PC.
I saw that the error gives it on all .psd files (Adobe Photoshop extension) of which my Cloud is full.

I look forward to receiving your welcome reply.
Thank you.

I attach an image of the error that is displayed to me by the app installed on my PC
Thank you

Massimo Marrone - Italy

Help Me!! please…

can someone help me please !!!