Tried to open default viewer to view a web page from Notepad++ from File->Open in default viewer menu, but kept getting “Another instance of Notepad++ is already running. Please close other instances of Notepad++ before launching Notepad++ portable.” Checked my running processes, but nothing. Found an answer on Stack Overflow website, but trying the direct application link rather than launcher link didn’t correct it. Removed the plug-ins folder and no change.
Found that I had Notepad++ installed on external drive and hard drive of computer. Uninstalled both (no uninstaller in control panel), then had to deleted approximately 100 registry keys due to plug-ins, and then restarted laptop. Reinstalled the desktop application (not portable one) on external drive and had same issue.
What could be causing this? My default browser is Chrome, so I went to open the html file outside application and it came up! Opened Notepad++ and went to Run->Launch in Firefox and voila..the html file opened in the browser! Run-> Launch in IE and it comes up. Now I try Run-> Launch in Chrome and same error! This is probably and issue between a call to the default (chrome in this case) browser through the OS from the application.
I went and changed my default browser back to IE and tried File->Open in default viewer in Notepad++ and it worked. Went to Run->Launch in Chrome and setup Chrome to be default browser again. Now it works in Notepad++ from File->Open in default browser again. This fixed the issue and now I can launch Google chrome as my default viewer again in the application. Hope this helps you solve the problem quicker, if you need it. Until next time, happy coding!