This is a help thread for people who will get the same problem:
Problem:I opened up GSB, the window popped up saying that a new version was available. I clicked download. It finished and said that it was successful. But now when I try to open it up it says: “Fatal Error: Operation EnsureDirectoryExists failed.” I have- or, more properly, had, version 1.50. I am assuming it was updating to the version 1.55 I have been reading about here (and I found it was after I got it to work).
Fix: I right clicked on Gratuitous Space Battles and selected “Show Package contents”. Then I took everything out of Contents/Resources/data/installs, and moved the GratuitousSpaceBattles folder out of the Users/Your name/Library/Preferences folder. I opened up the game. It worked, but the campaign background was gone (I had taken away what told it where to look). I moved everything back and now it works fine.
And I end with a question: Does Version 1.55 for mac come with the ship hull editor? its not in options…