Self-setting successCount on a command block leads to a crash. The command blocks's "previous output" is not wiped with the application. The command block fills up, leads to crash.

blockdata ~ ~ ~

[22:05:25] Block data updated to: {Command:"blockdata ~ ~ ~

",id:"Control",TrackOutput:1b,LastOutput:"{"extra":[{"translate":"commands.blockdata.success","with":["{Command:\"blockdata ~ ~ ~

\",id:\"Control\",TrackOutput:1b,CustomName:\"@\",SuccessCount:1,z:-74,y:1,x:663,}"]}],"text":"[22:05:09] "}",CustomName:"@",SuccessCount:1,z:-74,y:1,x:663,}