if you face an error about could not load file or assembly ..... incorrect format during publishing any web site that is prepared on 32 bit operating system to x64 bit OS. check follow: 1- be sure that project built in CPU : x64(Not CPU any or x86) architecture via MS Visual Studio (from Project Property>Build) 2 - check follow in IIS run on x64 bit; Set App Pool Advanced Settings "Enable 32-Bit Applications" to True. Set Website .Net Trust Levels to "Full Trust" cheers !!! P.S:Please do not hesitate to share your comments.