Post-job: Cache fails

In the pic above Iam trying to cache my yaml.lock file to reduce runtime and Iam using the azure devops docs to do that.

The first Cache step seems to work fine and there is "a cache miss" and then it runs yarn install.

But the Error comes in the Post-job: 

Its taking 10 minutes and then timing out i think.

--Note--

Iam using a self hosted agent here and i added GNU Tar and 7-zip and restarted the agent.

--End Note--

I dont know if the above had something to do with my problem. But it didnt work before or after.

Can anyone help out here?