Docker error: invalid reference format: repository name must be lowercase

Question

Ran into this Docker error with one of my projects:

invalid reference format: repository name must be lowercase

What are the various causes for

Answer 1

In my case was the -e before the parameters for mysql docker

docker run --name mysql-standalone -e MYSQL_ROOT_PASSWORD=hello -e MYSQL_DATABASE=hello -e MYSQL_USER=hello -e MYSQL_PASSWORD=hello -d mysql:5.6

Check also if there are missing whitespaces