iOS5 convert project to ARC fails due to "Error in format of file" How to fix?

I got a project with 49 source files that I'm trying to convert to ARC using edit>refactor>convert to arc. I click "pre-check", there are no errors, and the target compiles.

Xcode goes through "generating preview", compiles all 49 source files, then shows me 1 (or 2) file in the review changes list. This is a .h/.m file. That one appears correct. There are no other files on that list and I see.

When I clic开发者_高级运维k save, the window closes, and the project tries to build, but fails with error:

Error in format of file: ...-arc.migrate/remap

These errors appearing in all files

If I try to build the project, i get ~350 errors saying "retain, release not allowed in ARC"... Please help!

How do I convert the entire project to ARC at once?

Update: After cleaning the project a bunch of times and changing the deployment target to iPhone 5 simulator, I was able to see all files in the "save changes" list.

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I found a way to answer this question and am posting it here for clarity:

After cleaning the project a bunch of times and changing the deployment target to iPhone 5 simulator, I was able to see all files in the "save changes" list.