AWS responds "The request signature we calculated does not match the signature you provided"

The first thing to do is check if your string-to-sign matches the one AWS expects.

If it does, but you're still getting that error, try regenerating your Secret access key until you get one without any special characters. No slashes, no plus signs, just letters and numbers. In some cases (such as mine) that helps.

Go to AWS IAM Users Management Console, click your user, go to the Security Credentials tab, scroll down to Access Keys, delete the ones you don't need (the limit per IAM user is 2) and finally click Create Access Key. Repeat until you get a clean, alphanumeric one