When uploading files, you may occasionally see an "Unknown Error". No one wants to see that. We certainly don't want you to see it. But when this happens, it usually means the browser literally cannot figure out what the error is.
Fortunately, we have some experience with this and can point you to some potential issues to check:
Most common is uploading a folder with a significant number of files (thousands) in it. If this is the case you'll want to take a look at this help article we've put together: https://knowledge.pinata.cloud/en/articles/5509412-how-to-upload-a-large-folder-by-running-a-local-ipfs-node
The next most common reason is you are uploading a very large file (more than 10 GB). You should not hit this error for large files as long as your network connection is strong, but if there is even a tiny blip in your connection in the time (and this can take hours on some connections) it takes to upload, the upload will fail and you will see the dreaded "Unknown Error". There isn't much we can do to help you here, but you can take steps on your own to ensure a strong connection: https://www.cnet.com/home/internet/upload-speeds-explained/