What's the meaning of these two error messages?

I’m doing a backup with a large number of small files to Dropbox.

Errors:                23
Checks:               630
Transferred:        33445

For some (see above), I’m getting the messages below:

Failed to copy: upload failed: unexpected end of JSON input


Received error: upload failed: too_many_write_operations/ - low level retry 1/10

What are these errors?

That is caused by a 500 server error from dropbox. It should be fixed (as in you’ll get the 500 error) in the latest beta.

That is rate limiting by dropbox. As you can see from the message, it should retry.

Thanks! I’ll try it.

That’s what I thought, thanks for the confirmation.