I have the same issue on 2 laptops (windows 10) following the last iTunes update. It was also around 26 April 2021.
I contacted Apple support over their online chat service and was told it was a conflict in my Firewall/Anti Virus software. I use McAfee Total Protection. Apple weren’t very helpful and this felt like I was being fobbed off.
So I contacted McAfee and they remotely checked my software and came to the conclusion that it was nothing to do with their software.
I went back to Apple online chat and they booked me a Genius session at my local Apple store for the same day. I took my laptop up and he logged onto their internet and we got it working. He said that I needed to give my Laptop “permission” to contact the grace nite server. As far as I know he just connected to the following address:
https://service.gracenote.com.
But when I got home it all went back to gracenote error 0x0. Grrr! My mcafee says this address is an insecure web address and I can’t see how to allow access or fix it. Is it a Microsoft issue?
My hunch is that until they update iTunes we will all be stuck with a useless version of iTunes. This means I know have a useless iPhone and useless music software on my laptop. Is there another provider? Because, If they (Apple) can’t admit and apologise that they have done something unknowingly wrong, then shame on them and their customer service. It’s unusual but I’ll wait and see if anyone from Apple contacts me.
Hope this helps the rest of the community.