For anyone else stumbling across this thread when googling for this annoying problem: the issue here is that using special characters in your password on the DataSource line is broken: Can’t use special character in password in the DataSource property · Issue #1541 · mattermost/mattermost · GitHub

As stupid as that is, the easiest way to work around it is to set a password consisting of just alphanumeric characters. You shouldn’t have much use for it outside this anyway, so as not to make it ridiculously insecure.