Sometimes users hit a bug in GnuCash that a developer can't reproduce. This bug may be triggered by something in the user's data file, but if the developer doesn't have access to the user's data file it can be very hard to figure out what the problem is exactly.
Of course, a user's data file contains private information that he probably likes to keep private.
The solution is to obfuscate the data in your data file. For the GnuCash xml data files, you can use the script by Adam Buchbinder below for that purpose.
The script has been moved here: https://github.com/Gnucash/gnucash/blob/maint/util/obfuscate.pl
The script will read in the file, process the data, and write the output on "stdout".