This bug was originally marked as duplicate of bug 161833, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.

Build: NetBeans IDE 8.1 (Build 201510222201)
VM: Java HotSpot(TM) 64-Bit Server VM, 25.77-b03, Java(TM) SE Runtime Environment, 1.8.0_77-b03
OS: Windows 7

User Comments:
GUEST: I'll be honest, this is my first time using Netbeans 8.1 on Windows 7 since about a year, so I have no clue where this error is coming from. I'm sending you this on the off chance that the Summary is useful to you.

I was having infinite background scanning, and read that deleting the jseditor2 module files from the Netbeans program files folder might help, which it did.

I restarted netbeans, and this error occured, but no background scanning was happening. It is well possible that these two errors are completely unrelated, as I haven't used my installation in a year, so I could have done anything, we don't know.




Stacktrace: 
java.lang.NullPointerException
   at org.netbeans.api.debugger.DebuggerManager.refreshDebuggerManagerListeners(DebuggerManager.java:1549)
   at org.netbeans.api.debugger.DebuggerManager.initDebuggerManagerListeners(DebuggerManager.java:1524)
   at org.netbeans.api.debugger.DebuggerManager.initBreakpoints(DebuggerManager.java:996)
   at org.netbeans.api.debugger.DebuggerManager.initBreakpoints(DebuggerManager.java:965)
   at org.netbeans.api.debugger.DebuggerManager.getBreakpoints(DebuggerManager.java:603)
   at org.netbeans.modules.python.debugger.breakpoints.BreakpointAnnotationListener.annotate(BreakpointAnnotationListener.java:143)