It’s not that trivial, and sorry I didn’t explain you properly. I’m not a native speaker, so I avoid type too much
Your .sifz file (“3.sifz”) points to/links to another .sifz file (“backgroundbooth.sifz”). Somehow, it stores the wrong relative path to that linked file. You said you didn’t move any file, so it’s a bug. I think it’s exclusive to Windows. Anyway we shall fix it as soon as we can discover the reason.
For solving your problem, you can change ‘by hand’ the filepath to “backgroundbooth.sifz”.
The sifz file format is a compressed version of sif file format. In its turn, sif is a text file with a XML contents: you can open a .sif file in Windows Notepad app (or notepad++ and alike), search for the wrong (and bizarre) file path to “backgroundbooth.sifz” and edit it to point to correct path.
You can get the .sif contents of a .sifz file by uncompressing it. Linux provides ‘native’ tools to do it.
As you’re a Windows user, you can use that site to convert the compression Synfig uses to the well-known .zip . The site I linked you (https://online-converting.com/archives/convert-to-zip/) changed a bit since last time I use it, but I think you can do it this way:
- Rename the problematic file “3.sifz” to “3.sif.gz”
- Access the converter website, upload the file to convert it to .zip
- Uncompress/Extract the contents: it’s should get a single file from the archive: a .sif file (even if it doesn’t have this extension)
- Change its extension to .txt and open in Notepad.
- Search for “backgroundbooth.sifz”
- Change the string with the correct path:
- it can be an absolute path (eg. “C:\Users…”), or
- a relative path:
- if they’re in same folder, just the “backgroundbooth.sifz” is enough;
- if “backgroundbooth.sifz” is in a ‘inner’ folder called “resources”, for example, replace the wrong filepath with “resources/backgroundbooth.sifz”; or
- if “backgroundbooth.sifz” is in “outer” folder: let’s say the parent folder, you should write “…\backgroundbooth.sifz” ("…" means parent folder)
- Save it
- Rename it with a .sif extension.
- Open it with Synfig Studio