WeChat Pay API key error

You can typically resolve this by resetting the API key in the WeChat Pay Merchant Platform and enabling WeChat Pay again. If the error persists after several resets, the cause is likely that the merchant ID associated with your WeChat Official Account does not match the merchant ID of the account used to get the API key. To fix this, re-associate your WeChat Official Account with that merchant ID. You can then enable WeChat Pay again.

You can find your WeChat Pay merchant ID on the basic account information page of the WeChat Pay Merchant Platform. To re-associate, go to WeChat Pay > merchant ID management in your WeChat Official Account. Click the associate more merchant IDs button in the upper-right corner, then click the start application link in Step 1 of the association process.