What does "Missing 'url' from library" error mean, adding external libraries?

Hey guys.

I'm following some online tutorials for my Arduino Uno, and after copying/pasting some new libraries into the "libraries" folder for Arduino, my IDE is telling me that "Invalid library found in C:\Program Files (x86)\Arduino\libraries\pitches: Missing 'url' from library" for all of the folders I moved in/overwrote. However, I can't find ANY information regarding this error online?

Does anyone know what "Missing 'url' from library" refers to here? Is it something to do with my path? Or do I have to update something?

For context, this is a 100% fresh install, with 0 sketches created or saved. I have done NOTHING other than transfer the libraries, and open the IDE. I'm also a complete beginner, so I'm not really sure how best to troubleshoot something like this.

There is a file at C:\Program Files (x86)\Arduino\libraries\pitches\library.properties which contains the library's metadata.

library.properties is required to contain certain fields and recommended to contain other fields. url is one of the required fields. A library is considered invalid by the Arduino IDE if its library.properties file is missing the url field.

You need to open C:\Program Files (x86)\Arduino\libraries\pitches\library.properties in a text editor and add a line that looks something like this (at any location in the file):


More information on library.properties: