Unable to use API of S3 bucket

It looks like you're encountering the "IllegalLocationConstraintException" error when trying to interact with an Amazon S3 bucket. This error occurs when you're trying to access a bucket from a different AWS region than where the bucket exists.

The specific error message indicates that you're sending requests to an endpoint in one region, but specifying a location constraint (ap-south-1) that doesn't match that endpoint's region.

To resolve this issue:

1. Confirm the actual region of your S3 bucket. You can do this using the Amazon S3 console or the AWS CLI.

2. Make sure your API or SDK configuration is using the same region as your bucket. Your API calls must be directed to the endpoint that corresponds to your bucket's region.

3. If you're creating a new bucket, ensure that the region specified in your API call matches the endpoint you're using.

4. If you're using the AWS SDK, update your client configuration to use the correct region.

Remember that S3 bucket names must be globally unique across all AWS accounts, so if you're creating a new bucket and getting errors, you might need to choose a more unique name.

For your REST API implementation, ensure that all your S3 API calls are directed to the correct regional endpoint that matches your bucket's location.
Sources
Resolve the Amazon S3 “IllegalLocationConstraintException” bucket error | AWS re:Post
Error responses - Amazon Simple Storage Service
S3 Bucket Creation Failed - BucketAlreadyExists Error | AWS re:Post

This error typically occurs when trying to access an Amazon S3 bucket from a Region different from the bucket's Region. To resolve this, you must update your API or AWS SDK to match the bucket's Region [1]. For all AWS Regions launched after March 20, 2019 you need to specify the endpoint-url and AWS Region with the request you can find a complete list of Amazon S3 Regions and endpoints in the documentation [2].

References:

[1] https://repost.aws/questions/QUKgr9fG6fSimVSUqK9fvkwQ/illegallocationconstraintexception-error-when-using-s3-create-bucket-code

[2] https://docs.aws.amazon.com/general/latest/gr/rande.html#regional-endpoints

[3] https://stackoverflow.com/questions/77651471/aws-boto3-error-illegallocationconstraintexception