The provided model identifier is invalid

The error you're encountering, "The provided model identifier is invalid," can occur for several reasons, even if you previously had access to the models. Here are some potential causes and solutions to consider:

1. Model Access Expiration: It's possible that your access to certain models has expired or been revoked. Even with a free trial account, access to foundation models in Amazon Bedrock isn't permanent and may need to be periodically renewed.

2. Region Mismatch: Ensure you're still working in the same AWS region where you initially requested and were granted access to the models. Not all models are available in every region, so if you've switched regions, this could cause the error.

3. Model ID Format: Double-check that you're using the correct model identifier format. Sometimes, updates or changes to the service can affect how model IDs should be specified.

4. Account Status: Verify that your free trial account is still active and in good standing. There might be limitations or changes to your account status after a certain period.

5. IAM Permissions: Although you mentioned having access before, it's worth checking if there have been any changes to your IAM permissions that might be affecting your ability to use Bedrock models.

To resolve this issue:

1. Go to the Amazon Bedrock console and navigate to the "Model access" section.
2. Verify that you still have "Access granted" status for the models you're trying to use.
3. If access has been revoked, request access again for the specific models you need.
4. Ensure you're using the correct region where the models are available and where you've been granted access.
5. Double-check your IAM permissions to make sure you still have the necessary rights to invoke models in Bedrock.

If after checking these points you're still encountering the error, it may be helpful to contact AWS Support for further assistance, as there could be account-specific issues that need to be addressed.

Sources
Why am I getting "The provided model identifier is invalid" | AWS re:Post
I can't activate LLM models in AWS Bedrock | AWS re:Post