Are you asking why the signature failed when downloading the electronic invoice? The reasons are as follows:

1. The reason for the electronic signature failure is network reasons or a failure of the tax bureau’s signature verification system. During the process of uploading the invoice to the Internet, the tax digital certificate will fail to add a digital signature to the electronic invoice. Failure of the tax bureau's signature verification system will also cause the signature verification to fail.

2. Software setting problem. There may be some omissions when setting software parameters, such as errors in certificate, certificate password, signing authority and other information, resulting in signing failure.