As @decoderman said, you cannot edit it directly. However, you can run regedit (Registry Editor) Select the appropriate registry entry, or hierarchy level File | Export > File name = blah.reg Open blah.reg in Notepad++ Edit the text save exit Either In file explorer, double-click on blah.reg to auto-import it or, in RegEdit, File | Import > File name = blah.reg However, some registry edits require further action (like a reboot) to take effect. If you already have the .reg file, you can just edit it directly in Notepad++, and then follow the Either-instructions to bring it into the active registry. WARNING: If this wasn’t intuitively obvious to you to begin with – if anything I said above came as new information (e.g., if you didn’t already know how to export/import .reg files or if you didn’t already know that .reg files were text files so could be edited directly with a text editor like Notepad++) – I would then strongly caution you against manual registry edits, because editing your registry is something to be done only if you know what you’re doing, and can cause your system to stop working. Use these instructions at your own risk. I make no warranty, express or implied.

@Mark-Beiley95 I would say here https://github.com/notepad-plus-plus/notepad-plus-plus/issues with a description how it happened and if it is reproducible or not. Cheers Claudia

One more followup, and perhaps it’s obvious to some readers. But now that the 64-bit version of NP++ is available, I got that and it had no trouble opening the larger file. Hope that may help some other readers.

When Opening Notepad++ Right Click it and click on Run as administrator… If the file really need admin privileges that should work (of course you will need to have an user with admin permissions)