How can I resolve issues with AWS Cognito's SMS Multi-Factor Authentication returning an invalid code or auth state?

How can I resolve issues with AWS Cognito's SMS Multi-Factor Authentication when it returns an invalid code or authentication state, and what are the common troubleshooting steps?

Resolving issues with AWS Cognito's SMS Multi-Factor Authentication (MFA) returning an invalid code or authentication state involves several troubleshooting steps. Here are some common causes and solutions:

Common Causes Incorrect IAM Role Permissions: The IAM role used for SMS configuration might not have the necessary permissions.

Unverified Phone Numbers: The phone number might not be verified in the user pool.

Network Issues: Network connectivity problems can prevent SMS delivery.

Service Quota Limits: Exceeding service quota limits for SMS messages can cause issues.

Configuration Errors: Misconfigurations in the user pool settings or SMS MFA configuration can lead to errors.

Solutions Check IAM Role Permissions: Ensure that the IAM role has the sns:Publish permission and that there are no service control policies (SCPs) blocking this action.

Verify Phone Numbers: Make sure that the phone number is verified in the user pool. Users should complete the SMS verification process before attempting to sign in2.

Monitor Network Connectivity: Ensure that there are no network issues affecting SMS delivery.

Review Service Quota Limits: Check if you have reached the SMS quota limits and adjust if necessary.

Review Configuration Settings: Double-check the user pool settings and SMS MFA configuration to ensure everything is correctly set up.