An Azure service that provides a hybrid, multi-cloud management platform for APIs.
Based on the response you captured, the code itself is at least being recognized: prepareRedeem returns HTTP 200 and identifies the product as Dark Souls. The failure happens later during the actual redemption transaction, where RedeemNow returns:
PUR
AbnormalOrderContentChange
isUserError: false
HTTP 400
That makes this look less like a browser/API issue and more like a problem in the Microsoft/Xbox commerce redemption flow for that code/account. The isUserError:false value is also worth noting, although that internal response by itself doesn't tell us the exact backend cause.
One thing to verify is the code's region versus your Microsoft/Xbox account region. Xbox games and other content obtained in one region may not work in another, so don't change your account region simply as a workaround.
You can also try redeeming the code directly through Microsoft's redemption page while signed into the intended Microsoft/Xbox account. Microsoft recommends its redemption troubleshooter/support path when a valid code cannot be redeemed.
Microsoft code redemption page and troubleshooting
If the same failure occurs there, I would contact Xbox/Microsoft Support and provide them with the 25-character code privately, the account/region, approximate UTC timestamp, and especially the correlation ID: aiVckUTG0w5wn2+nrEGW+s.44.4
They should be able to determine whether the entitlement/code is blocked, region-restricted, previously consumed, or failing in the Xbox 360 commerce backend. Don't post the actual redemption code publicly.
Also, since this isn't an Azure API Management issue, the Azure APIM community won't have access to the Xbox commerce backend needed to investigate that correlation ID.
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