I think there is a bug since v1.3.57.
I cannot download or open log files from my APM 2.6 anymore.
I tried different versions and PCs. Latest version that can open APM log files is v1.3.56
Somebody else has another problem with APM 2.6 where also that strange path appears “C:\users\michael…”
The path is the compile time location of the source code files, to help developer identify where the exception was thrown.
On the other hand, apm2.6 hw is not supported since 2015 October (when AC 3.3. came out). I don’t see any reason to keep the Mission Planner compatibility after three years. Just install an older version (1.3x) to use with APM hw.
Yes I know that APM 2.6 is not supported anymore. But I don’t see a reason not to be able to connect this hardware anymore. I can accept that there are no new firmwares but without working ground station, old hardware becomes completely useless. It is annoying to deinstall and install differend Missionplanner versions every week. With older versions I get in trouble with new Ardupilot firmwares for my pixhawks.
There are still many users of APM 2.6. I agree with your solution if somebody gives me money for replacing my old APM 2.6 and 2.5 
My old quads still fly very well with that old hardware.
