This week I bought a Canon 5D Mark III . The 5DM3 came with firmware 1.3.3 , can i use the magic lantern with this firmware?
Is there going to be a 1.3.3 update in the near future? I ran into the same issue, bought a 5d that had it already installed
Downgrade to 1.2.3 using EOS Utility 2.x included in EOS Digital Solution Disk 29.1A (or older).
Issue #2570 was marked as a duplicate of this issue.
Follow Walter Schulz's advice and downgrade to 1.1.3 / 1.2.3