Double-clicking an llblgenproj file in Visual Studio 2017 always opens the file in text mode and fails to open the default editor, which is set to "LLBLGen Pro Designer integrated in Visual Studio (Default)".

The only way to open the designer is to first click "Open with..." and then click the "OK" button in the Open With popup dialog.

In the open with dialog, what's the editor set as 'default' in your case?

As specified above...

"LLBLGen Pro Designer integrated in Visual Studio (Default)"

Oh sorry, I overlooked that.

So if you choose, open with and then pick that editor (even if it's set as default) it works? Hmm. That is strange. If you use File -> Open -> File in vs it does the same thing? With all llblgenproj files you have? I do recall it remembers if an editor failed to load for a file and it then falls back to a text editor, and the next time you try to load the file again it goes straight to that text editor. (we saw that when creating the add-in, e.g. when it had a bug and threw an exception during load).

If you set, say, the xml editor as default, and then choose open with again and choose the normal editor, it does the same thing? You have both v4 and v5 installed btw?

File->Open->File opens in the designer. Setting XML editor as default and choose open with the designer => opens designer. Switching back to designer as default => opens text editor.

Only v5.3 installed.

Does this happen with a specific llblgen project? You can test that by creating a new dummy project.

If the answer is yes, then please open a Helpdesk thread and send us the llblgen project file. This might help us solve it for this specific file. However I assume, whenever an error/exception takes place, the same issue will pop up.