Crash : NSInternalInconsistencyException on UIFeedbackHapticOnlyEngine

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Fatal Exception: NSInternalInconsistencyException
ERROR: -[_UIFeedbackHapticOnlyEngine _deactivate] called more times than the feedback engine was activated

We've seen an uptick in crashes related to the preceding, especially since the launch of iOS 12 on the v10.8.1.1 release.

5b39f0b26007d59fcd66f058-fabric

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According to Fabric, 97% of the occurrences have been on iPhone devices running iOS 11, 3% on iOS 10.

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Researching the issue...

This SO post suggests that the crash can be associated to the "prepare" & "generate" methods being invoked on different threads.

Canvasing the app for UIFeedbackGenerator subclasses, I noted that there are a few places where feedback is generated in a closure, but most of these have been in place for quite some time:

• February 2017(a)
• February 2017(b)
• June 2017
• March 2018

The timing of most of these commits precedes the release of iOS 11.

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According to Fabric, this has not been observed at all within the last 9 days.

Moreover, It has not been observed on any WPiOS version after v10.9.0.1, and of those occurrences, all have iOS 11 or earlier.

Closing this issue.