Saxi wrote in post #12391644
I suspect he tried to open an image as a catalog, thinking he was importing. He is still fairly knew to Lightroom and is used to Paintshop.
That sounds like a likely culprit!
But, that is not good behavior on the part of Lightroom -- there have over the history of the app been bugs that have popped up and they have addressed them. Sadly, robust error handling often follows late in a software product lifecycle, although I found by hard experience that it should be a vital part of the core design.
Otherwise we see things like the above because the software "builders" have to basically go through every function of code, looking for ways that things can go bad, and add a robust way of handling things, all after the software is out on the market!
Fortunately Lightroom keeps well to a schedule of regular updates and provides fixes for this type of thing once they are identified and resolved -- they are much better at this type of stuff than a lot of apps who are just release it and forget about it.
So, my advice (and actually a helpful thing for the LR team) would be that you go to the LR site and file a Bug Report for this, describing what happened and what you suspect was the cause (trying to open an image as a catalog and not recognizing that problem and gracefully backing out).
And, hopefully a soon update will adress that and you will save some people some grief
!