A web search for "failed to execute child process gnome-software" turns up a number of links. What they have in common is that Program A tried to execute Program B, but Program B did not execute properly or was not present.
Perhaps if you looked in the log files, you could find more information about what application failed to execute. In this case, I'd suggest using journalctl for the search. Try executing the application, and, as soon as you get the error, search journalctl for the most recent entries;
this link will tell you more.
