Hope this helps someone else stuck with an older codebase.
Here’s a clear, helpful forum-style post you can use or adapt: Where to download log4net version 1.2.10.0? log4net version 1.2.10.0 download
Make sure to verify the signature if you’re using it in production. Also note that 1.2.10.0 is the file version as shown in DLL properties – the release is just called 1.2.10. Hope this helps someone else stuck with an older codebase
The file is log4net-1.2.10-bin.zip . It contains the 1.2.10.0 assembly. log4net version 1.2.10.0 download
Thanks!