MIGS主卡网关服务付款显示HTTP状态 - 400？

I have installed "MIGS master card gateway service payment" in our magento store it was working before upgrade now it showing HTTP Status - 400?

This question is old but for those who might run into this problem in the future, you get a 400 response when

1. The Access code is incorrect
2. The Secure Hash Secret used for that MID is incorrect.
3. The merchant is sending the transaction to the wrong URL (MTF instead of production, or vice versa)
4. The merchant is using the TESTMID details instead of the normal MID, or vice versa
5. The merchant is unable to generate the secure hash correctly

MIGS graduated to SHA256 from MD5. Make sure the plugin you use, or your code, accommodates that change.