NotImplementedError: only algorithm code 1 and 2 are supported. This PDF uses code 4

[demongolem-biz]

See PyPDF2. This version of encryption has still not been implemented. I see several workaround solutions such as use pikepdf to open and save the file, but to have a nondestructive version would be more proper.

[likerun-cell]

I also ran into this problem, is there any good solution?

[pubpub-zz]

PyPdf4 support is not active
You should move to pypdf