Please assume the people responding to you here know what they're talking about.
You have a 250 MB IPCC PDF in your library, and that's what's hitting the quota. You can see the filename for yourself in the error message if you click on the sync error icon in the toolbar.
Yes, but this PDF is on Zotero since 06/06, this is why I answered that I´m not trying to upload a new PDF of 250 MB now. It was already there and I was using Zotero, normaly. This erros started to appear today after Zotero´s update.
It has nothing to do with an update. A 250 MB file would obviously put you way over your free quota. You didn’t notice the error earlier or weren’t syncing. There’s nothing else to discuss here. I explained above how you can fix it.
Upgrade Storage
You have a 250 MB IPCC PDF in your library, and that's what's hitting the quota. You can see the filename for yourself in the error message if you click on the sync error icon in the toolbar.
Add a storage subscription or delete that file and empty that trash.