fusion crashes when i open a specific file

hello.
when i open a specific fusion 9 file [i've tried opening from the 'recent files' list, the 'open file' browse, and by double clicking the icon in my file manager] the whole program shuts down. it just leaves the screen: there's no message or anything.
the last time i had the file open was earlier today. i saved the file, then i successfully rendered the whole file, then i closed the fusion program.
when i went back to work on it agains is when the problem started. i tried restarting the computer...same results. i tried turning computer off, waiting 10 minutes, turning it on...same results.
i think there is no autosave version because i successfully saved the file last time i had it open.
any help in term of why this is happening or what to do about it [can i convert it to script and open it that way somehow? ... ?] would be very appreciated.
thanks.

I've seen this happen once or twice before. Often the comp can be salvaged with a text editor. You'll need a programmers editor, such as Notepad++. You could go through and look for missing brackets, but usually the simplest approach is to just extract the Tools table.

Open the comp using your code editor and set the Language to Lua. If you're using Notepad++, that will let you collapse tables, which makes extracting the bits you need easier.

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Here, I've got the comp open, and I made a New, empty file. To move the empty file to the other pane like I have here, right-click on its tab and choose "Move to Other View."

I've indicated the Language menu, where you can select the Lua language, and a '-' button next to the Tools table. If you click that -, the table will collapse to a single line. Put your cursor on the line below, then shift-click the beginning of the Tools line. Although most of the code is hidden, that will select it all. Copy and paste into the blank file in the other View. Change the language of that file to Lua also to again activate syntax highlighting.

The first line of your new file should have "Tools = {". If you place your cursor next to the curly brace, it should highlight both the brace and a line on the left, which indicates the end brace. Scroll to the end of the file to verify that the very last brace is also highlighted:

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It might be hard to see there, since the blue is so close to black, but you can see that the dark blue line ends at that last brace.

Add one more closing curly brace } to the very end of the file, then scroll back up to the top, add a line above "Tools = {", and put an opening brace { at the beginning. Change line 2 to read "Tools = Ordered() {".

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Once that's done, you should be able to copy the code and paste it into a blank Fusion comp to get your nodes back.

You'll lose any comp-specific preferences, so double-check the Frame Format and frame rate settings.

If you ever need a reminder of exactly what it should look like, just make a couple of random nodes, copy them, and paste into your code editor to see what the structure should be.

Edit: If this process doesn't work, then probably there was a brace or a comma that was truncated somewhere, or there's a node with corrupt inputs. Scan the file looking for non-standard text—everything should be human-readable, and if you find something that isn't, that's likely the cause of the crash. Fixing that might be more difficult, but it's often still possible.

wow, thank you bryan for that thorough answer.
i will pour into the attempt to save it this weekend.

ok, i jumped ahead and dove in tonight.
thank you sooooo much again. i finally got it. the initial process didn't work, but thanks to your closing note, i kept at it by putting half the nodes into a fusion comp, and repeatedly halving them until i found the one that didn't work. it was a saver node. no idea what was wrong with it [it wasn't brackets or indecipherable words], but everything else is back in and hooked up and working. you're the hero of the day.

Good on you for working it out with the binary search! You've taken your first step into a larger world.