I have also encountered such a problem, and I don’t know how to solve it, but here is what I did:
- Turn off CPC and then turn it on again
p>
- Go to the "File Management" (an icon) above, find your patent application (note that you must select a new application), click "Export File" to export a Zip file
- Go back to the new application, import the Zip file, and then try it again. That is, sign again. When signing, I checked "Perform format verification"
- Before I clicked send in "To be sent", I clicked "Fee Calculation". But I think it may not have any inevitable connection with being able to send successfully.
- Click Send and you’re done