This is perhaps the biggest quirk about SourceTree that I have found. I make changes to my branch and commit them. I do this a couple of times and then click the push button. By default it selects all of my branches. I may have ten or so branches but only commits on the one I am working on. I click ok and it pushes and then comes back with an error message that says my push failed. I go and pull and try it again. Still failing. Low and behold my push actually succeeded but a push to a branch with no changes failed. First I am not sure why a push of no changes should fail. Secondly why would they need to be checked anyway and why do I get a big red bar and have to click cancel when everything is just fine?

This is even more confusing if you use the check box that says push commits immediately. It will say that your commit succeeded but your push failed. In reality both succeeded and a push to a branch with no changes on it failed. I am used to this by now but i am reminded about it when people new to SourceTree are watching me.

Them: "Oh your push failed."
Me: "Actually it worked it just looks like it didnt work"
Them: "Oh, but there was a big red bar and a pop up saying it didnt work"
Me: "Yeah I know"

Yeah, so it is trainable but not very intuitive.