boto.exception.NoAuthHandlerFound: No handler was ready to authenticate

TL;DR: boto v2 found no AWS credentials anywhere it looks. Set AWSACCESSKEYID and AWSSECRETACCESSKEY in the environment, or add them to ~/.boto, and retry.

boto.exception.NoAuthHandlerFound: No handler was ready to authenticate. 1 handlers were checked. ['HmacAuthHandler'] Check your credentials

Fix it

1. Set the pair: export AWSACCESSKEYID to your key id and AWSSECRETACCESSKEY to your secret. Expected: set.
2. Or write ~/.boto with [Credentials] awsaccesskeyid and awssecretaccesskey entries. Expected: boto reads it.
3. Retry the call. Expected: authenticates.
4. Long-term: migrate to boto3, whose credential chain and errors are better documented.

When this applies

• The error is NoAuthHandlerFound from import boto code.

When it doesn't

• You use boto3: the equivalent error is NoCredentialsError.
• Credentials exist but the request is rejected: check the key values.

Compatibility

• boto 2.x.

Why it happens

boto v2 checks handlers that can sign the request; with no credentials configured, no handler qualifies, and it reports this instead of a clearer message.

Edge cases

• ~/.boto vs ~/.aws/credentials: boto v2 prefers its own file; boto3 prefers the AWS one.
• IAM roles on EC2 work with boto v2 via the metadata service, same as boto3.

Reported in a troubleshooting doc (doc:guyrutenberg.com duply credential error): duply credential error: boto.exception.NoAuthHandlerFound - fix and cause. The verified fix: Asked on Stack Overflow by developers getting NoAuthHandlerFound from boto. The verified answer: boto found no credentials in env vars or config files, so set AWSACCESSKEYID and AWSSECRETACCESSKEY or add them to ~/.boto. Source: the linked Stack Overflow thread. Source: https://www.guyrutenberg.com/2017/10/12/duply-credential-error-when-using-amazon-s3/comment-page-1/ Thread ref: doc:guyrutenberg.com duply credential error