Hello,
Apple rejected my app due to below resune.
Guideline 2.1 - Performance - App Completeness
We discovered one or more bugs in your app when reviewed on iPhone and iPad running iOS 12.3.1 on Wi-Fi.
Specifically, we were not able to log in due to an error.
Next Steps
To resolve this issue, please run your app on a device to identify any issues, then revise and resubmit your app for review.
If we misunderstood the intended behavior of your app, please reply to this message in Resolution Center to provide information on how these features were intended to work.
For new apps, uninstall all previous versions of your app from a device, then install and follow the steps to reproduce the issue. For updates, install the new version as an update to the previous version, then follow the steps to reproduce the issue.
Resources
For information about testing your app and preparing it for review, please see Technical Note TN2431: App Testing Guide.
For a networking overview, please review About Networking.
My live app ( version 1.4.1) is login with same credentials and test flight app (version 1.4.2) is also login with same credentials. So what is the issue with login from your end I can't understand. Can you please help me with that. I tried with iOS 12.3.1 with Wi-Fi.