CareerCup

There could be 2 reasons of this happening:
1. The test environment is different from Production environment.
Ex. Access & Permissions in Prod environment, Memory limitations, ELB timeout, Single & Multi-tenant configs etc

2. Person Testing missed to test the scenario which was tried by the customer or the person working in Production environment

There might be an issue regarding Timezone server time.

OutOfMemoryError came in production, which QA was not able to find it.

There may multiple reasons for this, if you could tell more about the bug, it will narrow down our issue

One common reason for this behaviour is production data schema differs when we add new features and if not updated or correctly replicated on all servers it might create production issues.

There will be multiple reasons for this
1)Production environment is different from testing environment.
2)Exhaustive testing is also not possible.
3)Tester doesn't test that scenario or he may test it in a different way.

sdf

Due to execution priorities, the testing surrounding the bug found in Production may not have been tested in the Dev/Test environment. You also may find that changes to one module may have impacted another module which was not known or communicated properly.

1. Code is not migrated to Production environment properly , there might be some issues in migrating the code for that particular functionality where the issues caught.
2. Compare the test data used to Production and Test environment , if data is different from test environment and working fine in Test Environment then that might be Test Data set up issues in Production.
3.If tester has missed the scenarios test in Test Environment check the requirement given for the application and check whether it is mentioned in requirement. If functionality or different test for that functionality is not mentioned in requirement then that requirement gap.

Verify Prod Environment:
1) Check if the issue reported in Prod environment is a valid defect
2) Check if valid inputs were used in Prod environment
3) The bug reported could be out of FRD scope or it could be a enhancement feature

Verify Environment:
4) Verify if Prod and QA had the same environment or is there any difference
5) Try clearing cache, browser history and check if bug is getting reproduced in Prod

Verify Internet:
6) Verify if Prod and QA had similar internet connectivity setup (like VPN, LAN, Wifi)
7) Verify if QA Location and Prod Locations are same (Onshore/Offshore)

Verify Deployment::
8) Verify if QA and Prod had same build or if different versions are deployed
9) Verify if there was any code missed during deployment from QA to Prod
10) If none of the above is the reason, then possibly QA would have missed it, so log a new defect with priority