I installed meltano via pipx. I somehow can't install plugins anymore and always get the following error? Any idea what the reason could be?

Python.h: No such file or directory

just means that

pip install

is trying to build some python package from source rather than using a binary wheel. In order to build python packages from source, there is a high chance that a C compiler will be invoked. Because Python is just C 😁 ... The C compiler then needs the Python development header files to be present, which are not present in your case. I'll take a guess and say that you using something like Ubuntu. Ubuntu (and many other old school Linux OS) do not install development headers by default. You'll need to manually install them. Something like:

sudo apt-get install build-essential python3-dev

should resolve your problem

I've lost lots o time on this one, easiest fix for most is to install a compiler and have I think ubuntu it's

sudo apt install build-essential

ciso8601 has a wheel I think but only for certain versions and on a certain version of Python. https://pypi.org/project/ciso8601-wheels/2.2.0/#files fwiw I think someone published the wheels seperately, no idea whether to trust them or not

Bumping

singer-sdk

to >0.11.0 should get rid of the offending dependency. I’ve logged https://github.com/MeltanoLabs/Meta/issues/25 to ensure all MeltanoLabs have up-to-date dependencies