I cannot load proper litematica files. I get the error as seen in the title and the attached screenschot. I've review past threads with similar content and all of them have a issues with .schem or .schematica type files but I am unable to open proper .litematica files which are supposedly built for this mod?

The specific schematics I am unable to load are: https://www.youtube.com/watch?v=mZWlTU4gz3o and https://www.youtube.com/watch?v=hVHFIfZAL54

I am using the latest version of litematica and malilib, and i am unable to load the litematica file on papermc server or vanilla singleplayer.

I hope you will be able to resolve my issue. Thank you very much!

Both of those schematics load fine for me. Make sure you are not extracting them accidentally at some stage. Your browser (or notoriously at least Google Drive) may see that they are gzip-compressed data and it might offer to (or decide to) uncompress the file. The current Litematica version is not yet prepared to load uncompressed NBT data. But I'll probably need to add that support as this keeps being an issue for some users, when some program decides to uncompress the schematic files.

This is now fixed (if it was caused by uncompressed files) in the 2021-09-06 build for 1.17.1.