Exception on imageWithContentsOfFile - Acquire pthread write lock failed

Question

I am reproducibly getting an exception on this line

UIImage * image = [UIImage imageWithContentsOfFile:path]; // Always main thread

The exception is not fatal, if breakpoints are disabled the app continues normally. I presume the exception is caught in Apple's code.

The message logged is:

< Error >: ImageIO: CreateMetadataFromXMPBufferInternal  
Threw error #11 (Acquire pthread write lock failed)

Stack-trace:

• The code is accessing a file path that the ASI Networking library owns.
• There is another background ASI thread thats checking for existence of the the URL string but I don't believe its actually writing anything to disk.
• The code is iterates over 8 successfully, then fails on the 9th.

Anyone seen this issue before or know whats causing it?