AWS S3 CLI - Could not connect to the endpoint URL

first you use 'aws configure' then input the access key, and secret key, and the region. the region you input would be important for this problem. try to input something like 's3.us-east-1', not 's3.us-east-1a'. it will solve the issue.

You probably have something wrong in your default profile for the default region.

Check your file at ~/.aws/config, you have something like

[default]
region=us-east-1a
...

Fix the region to region=us-east-1 and then the command will work correctly

If none of solutions given above works,also check your permissions and firewall settings. In my case adding proxy environment variables did the job.

For Linux or mac

$ export HTTP_PROXY=http://<YOUR PROXY IP>:<PORT>

$ export HTTPS_PROXY=http://<YOUR PROXY IP>:<PORT>

For Windows

set HTTP_PROXY=http://<YOUR PROXY IP>:<PORT>

set HTTPS_PROXY=http://<YOUR PROXY IP>:<PORT>