Doom Builder 2 is pretty stable and works great most of the time, but sometimes it does lock up and crash. If you are experiencing a crash and need to recover some lost progress, try following these steps!

This guide was adapted from This Forum Post from jmickle66666666

Try avoiding closing Doom Builder before you start this process. We don’t want it accidentally messing up the files we are going to be accessing in this guide.

Step 1: Make hidden items visible in Explorer

If you don’t already have hidden files and folders visible in Windows, enable them through Folder Options or simply open a new File Explorer window and go to the View tab on the ribbon and check the Hidden items checkbox. (see screenshot)

Step 2: Navigate to your AppData folder

This should be something like C:\Users\%username%\AppData\Local\Temp

You can also type the directory in manually if you’d prefer.

Step 3: Find the Doom Builder temp folders

You should have a lot of different things in this folder (mostly unrelated to Doom Builder). Doom Builder should create some folders that are 8 characters long. Mine were lowercase. Here’s a screenshot of mine:

Step 4: Find the one that is most recent

Check the Date created and Date modified on each folder to find the one that you are trying to cover.

Step 5: Recover the files

Inside the folder, there should be some files. Locate the .tmp files and copy them somewhere safe. If you can’t tell which ones are the right ones, copy them all.

Step 6: Rename the files

Now take those files you copied and change the file extension to .wad. Try to open each one up in a separate Doom Builder window to make sure you got the one you wanted.

Step 7: Cleanup

You may need to rename the file to something normal and maybe even add the current date. You will have to add any additional external resources to your map again on your configuration page.

Conclusion

Alright! We recovered from a crash and didn’t lose too much progress! Doom Builder creates these .tmp files every time you change the level so recovering this way is pretty safe usually.

Remember to save often!

One minute you’re working in GZDoom Builder’s Visual Mode, you fumble some keys accidentally, and now skies, dynamic lights, slopes, and 3d floors are all gone!!! What the heck!!! I would do this every once in a while and not know how to turn it back on. After some digging, I found that the TAB key toggles these features being rendered or not in Visual Mode.

Hopefully this info helps you out!