At the end of an OTDR test you see this (or similar) error message:
DotNet error: Overlapping Events
During the analysis at the end of a measurement.
This error message can sometimes occur when testing with long pulse-widths and/or shorter launch cables while testing longer fiber links.
Depending on the link you are testing, you can try with a shorter pulse, however if the link is quite long, then you may need to use a longer launch cable.
See below a general guide that can help select the appropriate pulse width and launch cable length for different fiber lengths.