django OSError: no library called "cairo" was found on windows

Starting from Python 3.8, dll's need to be added separately. Added GTK+, MSYS2, Visual Studio C Compiler and Uniconverter. But, nothing seemed to work. Finally, got it working after putting the script for calling add_dll_directory.

import os

def set_dll_search_path():
   # Python 3.8 no longer searches for DLLs in PATH, so we have to add
   # everything in PATH manually. Note that unlike PATH add_dll_directory
   # has no defined order, so if there are two cairo DLLs in PATH we
   # might get a random one.
   if os.name != "nt" or not hasattr(os, "add_dll_directory"):
       return
   for p in os.environ.get("PATH", "").split(os.pathsep):
       try:
           os.add_dll_directory(p)
       except OSError:
           pass


set_dll_search_path()

Source: PyCairo Windows Python3.8 Import Issue

Installing GTK+ didn't work for me. I solved this problem using UniConverter2.0. My environments is

• Python 3.7
• Windows 10 x64

1. Install uniconvertor-2.0rc4-win64_headless.msi,
2. Find the "dll" sub-directory under the UniConverter installation path.(In my case, C:\Program Files\UniConvertor-2.0rc4\dlls)
3. Add this "dll" path to the system path.
4. Close VSCode and reopen the project.
5. Try to run the server again. Enjoy!

WeasyPrint needs the Pango, cairo and GDK-PixBuf libraries. They are part of GTK+ (formerly known as GIMP Toolkit), and must be installed separately.

After installing GTK+ libraries, do :

python -m weasyprint http://weasyprint.org weasyprint.pdf