How to resolve following issue : 'Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' error

Question

getting this issue for crystal report: 'System.IO.FileLoadException: Could not load file or assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692fbea5521e1304' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'...i have added log4net.dll on azure server via filezilla... what steps to be done to resolve this issue