WeChat Pay error: "appid and mch_id do not match. Please check and try again"
When saving your WeChat Pay payment method settings, you might receive the error appid and mch_id do not match. Please check and try again. This error indicates that your WeChat Official Accounts Platform and WeChat Pay Merchant Platform accounts are not associated. Follow the steps below to associate the two accounts.
Log in to the WeChat Pay Merchant Platform. From the top menu, navigate to product center > AppID account management > my associated AppID accounts, and click associate AppID.
If an Official Account is already associated, verify that it is the correct account by checking its Nickname and Account Type.
On the next page, enter the AppID and select the checkbox to accept the agreement.
To get your AppID, follow these steps:
Log in to the WeChat Official Accounts Platform. In the left navigation pane, go to settings and development > basic configuration and copy the AppID.