Default save extension is "Normal Text" but Notepad++ is saving without an extension
New style save dialog has to be set to disabled for file extension suffix to work.
- Menu » Settings » Preferences
- "Default Directory" tab
- Uncheck "Use new style save dialog (without file extension feature)"
I found an answer that fixed this for me (versions 7.3.2, 7.3.3. and 7.4.2)
Settings->Preferences->Default Directory->uncheck Use new style save dialog…
(Source) Posted by (Claudia Frank)