-Turn CPC off and then on.
-Go in from the "file management" above (it is the icon), find your patent application (pay attention to choose a new application), click "file export" and export a Zip document.
-Go to the new application, import this Zip document, and then perform the operation again. That is, re-signing. I checked "check format" when signing.
-Before clicking "Send", I clicked "Cost Trial". But I think it may have nothing to do with whether it can be successful.
-Click Send, and it's OK.