I have been trying to make a song map with different parts. I got onto it today and all my progress from yesterday had been deleted. I wondered if I just didn't hit the save button. I tried to go back and fix it up and the moment I copied and pasted part of a song, I got a message saying “project could not save” with the options to “try again” or “download”. I have clicked try again several times and it still wouldn't save. I even did all of my song parts then put it in my backpack but the backpack said “error loading backpack” every time I would try to do it. I know it is not my internet because I can still make complicated codes and it still saves. I can also download it into my backpack and nothing happened. Please help!

My browser / operating system: Windows NT 10.0, Chrome 86.0.4240.193, No Flash version detected

I believe that the reason you're having this issue is that your song is over 10 MB in size. This breaks one of Scratch's project size limits (intentional size limits meant to prevent people from using too much Scratch server space, as it is limited and costs money), which is that no asset (a costume or sound) can be over 10 MB in size.

You can get around this by converting the sound to MP3, a format that takes up less space, but since you're making a MAP, there's a special consideration here due to the need for sound editing - and sometimes, you may have issues editing MP3s due to this:

Flowermanvista wrote:

An important note: If you convert a large WAV file (over 10 MB) into MP3, you will not be able to edit it in the Scratch sound editor. This is because the sound editor turns MP3s back into WAVs when you edit them, and if the resulting WAV would be over 10 MB, the edit will fail.

For your situation, I would recommend the following process:

1. Download your project.
   
2. Use Scratch Desktop to edit your sound. Scratch Desktop does not have the size limits of online Scratch.
   
3. Once the sound is edited, export it and convert it to MP3. If you do not have software on your computer that can do this, there are online converters - my personal recommendation is Zamzar.
   
4. Import the MP3 version (which should be under 10 MB in size) into your project, and delete the original version, which will likely be over 10 MB.
   
5. Modify the play sound blocks that are used so the sound plays.
   
6. Save and upload your project.