Hi Sushil,
I’ve experienced this error as well a number of times. Support fixed it for me a couple of times but the last time I was able to fix it by redeploying the app.
Support sent me this “Usually, when customers are seeing the AWS Access Key error the issue can be resolved by stopping and starting the application followed by a redeployment of the project.” As my app is in a sandbox, I’m not able to stop and start it, but the redeployment seemed to do the same.
Hope this helps!