If the prompt signature verification fails, first check whether your five parameters are complete. Timestamp, non-center, package, signType, paySign and signType must be MD5. The official demonstration is not MD5, but MD5, which is also a big pit. Of course, when I wrote in python, I used MD5 directly, and I needed six parameters when I signed paySign. The above five parameters, except paySign does not participate in the signature, appId is a capital I, which is a big pit. If this is wrong, the signature is bound to fail.
When signing, all English words must be capitalized so that the format will be correct.