Microsoft MakeCode

Lost main.ts code, is there a way to recover?

I was working on an experiment in JavaScript, and when I loaded the project today I got greeted by an empty Blocks screen, and the main.ts file is now empty :frowning:

This looks a bit similar to previous issues such as and, is there any current known bug that could trigger this? I’m using the live version, and it’s possible that I had never opened the Blocks view while working on it previously until I closed the editor.

Separately, is there any way to recover the lost source code? I was poking around a bit in Chrome Dev Tools in Application / Storage, and I found the IndexedDB storage (_pouch_pxt-arcade / by-sequence (go to last page), but that also has the empty main.ts.

I still have UF2 files, and mentions that the file format supports embedding sources - does Arcade do that, and if yes is there a tool to extract it?

Note to self: make sure to export or save as image regularly, I was trusting the editor to keep my work-in-progress safe…

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Edit: See UnsignedArduino’s response, simply drag&drop the UF2 file into, same as loading a saved image. I’m keeping the unnecessarily complicated method below for curiosity’s sake.

The UF2 file does indeed contain a copy of the source :slight_smile:

There’s likely a cleaner way to do that, but here’s how I got the data out using command line tools.

First confirm that the “source” magic number is present - this part isn’t part of recovering, but I wanted to check if it has source at all:

$ fgrep -ba $'\x41\x14\x0E\x2F\xB8\x2F\xA2\xBB' FILE.uf2
495620:[binary stuff]{"compression":"LZMA"}

Use the uf2conv tool to get a binary file:

$./ ~/FILE.uf2 --convert --output FILE.bin

Load the file into a binary-clean editor, search for “LZMA”, delete everything up to and including the final } of the JSON header, and save to FILE_SOURCE.lzma. In my case, the first bytes of the compressed data was ]^@^@ or 5d 00 00 80 00 in hex.

Then use the lzma and jq tools to get the source back:

$ lzma -d < FILE_SOURCE.lzma > source.json
$ jq '.["main.ts"]' < source.json > recovered-main.ts

(The source actually contains an extra JSON header, but the extraction worked anyway.)

It should be possible to wrap this in a recovery tool, but I wanted to save the steps in case this helps someone else, or future me if I get bitten by such a bug again…

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You can load UF2 files just like images.

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Ah, that would have been a lot easier :slight_smile: I guess I learned something along the way though.

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We had a bug like that before where it would switch to blocks without decompiling in some cases and delete main.ts, but to my knowledge that was fixed ~ half a year ago and I haven’t seen it since then; any more details you have would be super helpful if you have them in case there’s a sequence that regressed.

in case it’s helpful, one of the old ways to repro it if I recall correctly was to go from main.ts to another file (pxt.json or a locked file in an extension), then click the blocks toggle at the top; it wouldn’t notice there were edits made in ts and would just load up whatever was in the block file at that point.

And yes, dragging a uf2 onto the homescreen or using the import → import file button on the homescreen should both work :slight_smile:

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I don’t remember the exact sequence, but I think it was something like this:

  • create a new project
  • switch to JavaScript
  • add a second source file with “+” in explorer, use that for an added class
  • switch back between main.js and the second source js a few times. Don’t open Blocks mode.
  • close the editor
  • (later, after a computer restart) open the editor

At this point, the editor opened into an empty Blocks view.

Interesting, thanks! I’ll play around and see if I can find a way to repro, this is a very bad bug if it’s happening again!

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Thanks for investigating! I didn’t end up losing anything since I had the UF2 file due to testing on hardware, but this could be nasty for someone who’s only working with the emulator.

This has happened to me before - and it’s one way to circumvent the code too large for blocks error!

You can always ‘skip and go back’ if you put a syntax error into the ts and go to blocks (it will pop a dialog with “Discard and go to blocks or stay in javascript?”) but if it goes directly to blocks and throws stuff away without an option… that’s bad.