I've been looking at crashes in the hope of finding a pattern but couldn't. There's two reasons why this might be happening: either we're running out of memory when trying to write out the minidump, or we're running out of disk space. That's the two major issues I can think of which would lead to a failure in writing it out. An OOM situation should be catastrophic though, the Android kernel should kill the main process right away rather than have some allocations fail so I tend to think it might be the latter reason. To investigate this I'll try and cook up a patch that detects the amount of free storage on the partition where the minidump is being written and stores it as an annotation. If data from that annotation is not conclusive then I'll have to modify our crash-writing logic to report more granular errors and store those in an annotation too.