當把Web項目部署到Azure的時候，有時候會出現COULD NOT LOAD FILE OR ASSEMBLY的問題。這樣問題一般是由於某些依賴的Assembly的版本不對導致的，例如在開發機上可能同時安裝了MVC 3和MVC4。那么開發機不會出現問題，因為可以找到相應的Assembly。但是部署到Azure后就出現了依賴文件的問題。例如問題如下：
"COULD NOT LOAD FILE OR ASSEMBLY 'SYSTEM.WEB.WEBPAGES, VERSION=2.0.0.0, CULTURE=NEUTRAL, PUBLICKEYTOKEN=31BF3856AD364E35' OR ONE OF ITS DEPENDENCIES. THE LOCATED ASSEMBLY'S MANIFEST DEFINITION DOES NOT MATCH THE ASSEMBLY REFERENCE. (EXCEPTION FROM HRESULT: 0X80131040)"
Could not load file or assembly 'System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
如果你登錄到Azure的機器，然后修改注冊表HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fusion!EnableLog] (DWORD) to 1
你可以看到更詳細的信息，例如如下：
=== Pre-bind state information === LOG: User = NT AUTHORITY\NETWORK SERVICE LOG: DisplayName = System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 (Fully-specified) LOG: Appbase = file:///E:/sitesroot/1/ LOG: Initial PrivatePath = E:\sitesroot\1\bin Calling assembly : (Unknown). === LOG: This bind starts in default load context. LOG: Using application configuration file: E:\sitesroot\1\web.config LOG: Using host configuration file: D:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config LOG: Using machine configuration file from D:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config. LOG: Post-policy reference: System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 LOG: Attempting download of new URL file:///D:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/sts/5c2051b2/ac0bf06b/System.Web.Helpers.DLL. LOG: Attempting download of new URL file:///D:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/sts/5c2051b2/ac0bf06b/System.Web.Helpers/System.Web.Helpers.DLL. LOG: Attempting download of new URL file:///E:/sitesroot/1/bin/System.Web.Helpers.DLL. LOG: Attempting download of new URL file:///E:/sitesroot/1/bin/System.Web.Helpers/System.Web.Helpers.DLL. LOG: Attempting download of new URL file:///D:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/sts/5c2051b2/ac0bf06b/System.Web.Helpers.EXE. LOG: Attempting download of new URL file:///D:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/sts/5c2051b2/ac0bf06b/System.Web.Helpers/System.Web.Helpers.EXE. LOG: Attempting download of new URL file:///E:/sitesroot/1/bin/System.Web.Helpers.EXE. LOG: Attempting download of new URL file:///E:/sitesroot/1/bin/System.Web.Helpers/System.Web.Helpers.EXE.
解決方法查找項目的References下面各個Assembly，查找其版本
如果版本用錯了，那么需要重新引用正確的版本。
如果Azure上沒有安裝支持的庫或者runtime，需要把Copy Local修改成True，這樣dll就一並打包到Azure的package中。
有時候這些問題很難查，最好也是最花時間的方式是把整個包拉下來，通過ILSpy等工具查依賴項，細心仔細一個個查。