If you experiencing error “Could not load file or assembly ReportingServicesNativeClient” when you try to access Report Manager and/or Report Server in your SQL Server 2005 Reporting Services deployment, it’s most likely due to the fact that your Application Pool is configured incorrectly. More than likely you recently executed “cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 1” for some other project which ended up affecting SSRS without you even knowing it.
Here’s how I fixed this issue in my SSRS environment (please make sure to test this solution in your test environment before trying it on your production environment):
1. Open IIS Manager 7+
2. Click Application Pools
3. Select “ReportServer” from the list of app pools then click Advanced Settings
4. Under the General section find the property named Enabled 32-Bit Applications and set that to False
5. Register x64 version of ASP.NET – C:\Windows\Microsoft.NET\Framework64\v2.0.50727>aspnet_regiis.exe -i
6. Restart IIS
7. Test Report Manager
If it still doesn’t work:
1. Open the SSRS Configuration Tool and connect
2. Click Report Server Virtual Directory
3. Check mark Apply default settings then click the Apply button
4. If the Web Service Identity doesn’t show a green checkbox, click on it then make sure both Report Server and Report Manager are both set to the ReportServer app pool
That should do it.