Docker invalid tag value

Question

I'm trying to build the OwnCloud desktop client, for which the Owncloud docs explain that docker should be used:

Assuming you are in the root of the ownCloud Client’s source tree, you
can build an image from this Dockerfile like this:

cd admin/win32/docker
docker build . -t ownCloud-client-win32:<version>

I get an error with this exact command, so following the docker build docs I moved the dot to the end. But then I get the following error:

$ docker build -t ownCloud-client-win32:2.1 .
invalid value "ownCloud-client-win32:2.1" for flag -t: Error parsing reference: "ownCloud-client-win32:2.1" is not a valid repository/tag
See 'docker build --help'.

Why is ownCloud-client-win32:2.1 not a valid tag name?

I then just tried running docker build ., which runs successfully, but then I end up with an untagged image.

Does anybody have any idea how I can solve this?

ps. I don't know if it's important, but the relevant Dockerfile is here.

Answer 1

No uppercase. Try: owncloud-client-win32:2.1