Hey, I looked up the error code online and came across this: https://www.playstation.com/en-nz/get-help/help-library/error-codes/wc-40371-5/
It seems that the error means that the code you entered is not valid.
The article also states that there are a few other reasons why that error might be apearing such as:
The best suggestion would be to reach out to Playstation Support for further assistance. You can as well reach out to official support here for assistance with the matter:
Contact Us (Live Chat):https://support.activision.com/contact_us
Twitter Assistance: https://twitter.com/ATVIAssist
Facebook Assistance: https://www.facebook.com/ActivisionAssist?fref=ts
The live chat with an Activision agent should be available. The chat hours are from 11a.m. - 7p.m. Pacific Standard Time