After use of EpiServer Manager when I upgrade some site to 4.51 I got error in site with 4.50: === Pre-bind state information === LOG: DisplayName = ElektroPost.Wsrp (Partial) LOG: Appbase = file:///C:/praca/TestEpiServer LOG: Initial PrivatePath = bin Calling assembly : (Unknown). === LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind). LOG: Post-policy reference: ElektroPost.Wsrp LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/root/39a196fa/ff7128b1/ElektroPost.Wsrp.DLL. LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/root/39a196fa/ff7128b1/ElektroPost.Wsrp/ElektroPost.Wsrp.DLL. LOG: Attempting download of new URL file:///C:/praca/backup/WebSiteFIFF/bin/ElektroPost.Wsrp.DLL. LOG: Redirect found in application configuration file: 1.0.0.2 redirected to 1.0.0.3. LOG: Publisher policy file is not found. LOG: No redirect found in host configuration file (C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\aspnet.config). LOG: Using machine configuration file from C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\config\machine.config. LOG: Post-policy reference: ElektroPost.Wsrp, Version=1.0.0.3, Culture=neutral, PublicKeyToken=49582048716da0a9 LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/root/39a196fa/ff7128b1/ElektroPost.Wsrp.DLL. LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/root/39a196fa/ff7128b1/ElektroPost.Wsrp/ElektroPost.Wsrp.DLL. LOG: Attempting download of new URL file:///C:/praca/TestEpiServer/bin/ElektroPost.Wsrp.DLL. WRN: Comparing the assembly name resulted in the mismatch: Revision Number