Configuration failed with Guzzle\Http\Exception\ClientErrorResponseException

Entering the configuration settings on admin/config/services/openstack_storage I get

Guzzle\Http\Exception\ClientErrorResponseException: Client error response [status code] 401 [reason phrase] Unauthorized [url] <OS_AUTH_URL> in Guzzle\Http\Exception\BadResponseException::factory() (Zeile 43 von <drupal_root>/sites/all/modules/openstack_storage/vendor/guzzle/guzzle/src/Guzzle/Http/Exception/BadResponseException.php).

I took the values of the environment variables OS_AUTH_URL, OS_TENANT_ID,OS_TENANT_NAME
from openstack RC file source <OS_TENANT_NAME>openrc.sh

During the composer install I got the warning

Package guzzle/common is abandoned, you should avoid using it. Use guzzle/guzzle instead.
Package guzzle/stream is abandoned, you should avoid using it. Use guzzle/guzzle instead.
Package guzzle/parser is abandoned, you should avoid using it. Use guzzle/guzzle instead.
Package guzzle/http is abandoned, you should avoid using it. Use guzzle/guzzle instead.

the warning was resolved by updating to php-opencloud v1.14.1
(in openstack_storage/composer.json)
https://github.com/rackspace/php-opencloud/issues/541

But the Guzzle exception still remains.

Thanks in advance.