Fix for the type 'ILog' exists in both 'Sitecore.Logging, Version=1.2.0.30715, Culture=neutral, PublicKeyToken=null' and 'log4net,

I am sure while implementing custom logger you must faced this type of error.

To resolve this issue - Simply remove reference of Log4Net from the project.

As Sitecore.Logger already have refernece for this dll

Ref.

After removing the reference of log4net it will work, PFA