Log download via mavlink failing with "Error in log Object reference not set.."

[rmackay9]

I'm having troubles downloading logs from Rover-3.5.0-dev but I've seen it on other vehicles types as well.

I'm using a very recent version of beta MP

[meee1]

@rmackay9 can I get the missionplanner.log file as well when this happens?

[rmackay9]

I think it's happening when it's trying to download the last log in the list. In an attempted log download just now, the last log failed to download but then when I restarted the flight controller (with LOG_DISARMED = 1) I was able to download that previously-failed log.. but now the last log again failed to download.

P.S. I couldn't find missionplanner.log...

[meee1]

c:\programdata\mission planner\missionplanner.log even the tlog would be enough, as all the comm's will be in that

[rmackay9]

@meee1, OK. I've put the tlog and missionplanner.log here in dropbox: https://www.dropbox.com/s/zmvbv870vt0mgg9/mp-download-probs.zip?dl=0

[meee1]

2018-11-05 20:04:10,132 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 1-1 (:0) [40] 2018-11-05 20:04:10,154 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:10 PM 6 Log download in progress (:0) [40] 2018-11-05 20:04:11,102 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:11 PM 2 PreArm: Throttle below Failsafe (:0) [40] 2018-11-05 20:04:11,103 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:11 PM 2 PreArm: Hardware safety switch (:0) [40] 2018-11-05 20:04:11,103 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:11 PM 2 PreArm: Battery 1 low voltage failsafe (:0) [40] 2018-11-05 20:04:11,104 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:11 PM 2 PreArm: Battery 1 low voltage failsafe (:0) [40] 2018-11-05 20:04:12,133 INFO MissionPlanner.MAVLinkInterface - GetLogEntry Retry 5 - giv com True (:0) [40] 2018-11-05 20:04:12,240 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 2-2 (:0) [40] 2018-11-05 20:04:12,347 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 3-3 (:0) [40] 2018-11-05 20:04:12,453 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 4-4 (:0) [40] 2018-11-05 20:04:12,560 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 5-5 (:0) [40] 2018-11-05 20:04:12,671 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 6-6 (:0) [40] 2018-11-05 20:04:12,775 INFO MissionPlanner.MAVLinkInterface - GetLogEntry 7-7 (:0) [40] 2018-11-05 20:04:13,303 INFO MissionPlanner.MAVLinkInterface - 2018-11-05 8:04:13 PM 4 EKF primary changed:1 (:0) [Main Serial reader] 2018-11-05 20:04:21,462 INFO MissionPlanner.Log.LogDownloadMavLink - GetLog 6 (:0) [Log download single thread] 2018-11-05 20:04:21,770 INFO MissionPlanner.Log.LogDownloadMavLink - Got hbpacket length: 0 (:0) [Log download single thread] 2018-11-05 20:04:22,930 INFO MissionPlanner.MAVLinkInterface - start fillin len 319488 count 3550 datalen 78 (:0) [Log download single thread] 2018-11-05 20:04:22,931 INFO MissionPlanner.MAVLinkInterface - set count 3550 (:0) [Log download single thread] 2018-11-05 20:04:22,931 INFO MissionPlanner.MAVLinkInterface - count total 3550 (:0) [Log download single thread] 2018-11-05 20:04:22,931 INFO MissionPlanner.MAVLinkInterface - totallength 319488 (:0) [Log download single thread] 2018-11-05 20:04:22,931 INFO MissionPlanner.MAVLinkInterface - current length 319488 (:0) [Log download single thread] 2018-11-05 20:04:22,932 INFO MissionPlanner.Log.LogDownloadMavLink - Got Log length: 319488 (:0) [Log download single thread] 2018-11-05 20:04:22,934 DEBUG Program - FirstChanceException in: MissionPlanner (:0) [Log download single thread] System.NullReferenceException: Object reference not set to an instance of an object. at MissionPlanner.Log.LogDownloadMavLink.GetLog(UInt16 no, String fileName)

the cause is Got hbpacket length: 0 but now im trying to work out why this can happen in the first place