在新环境中从C＃WinForms应用程序读取加密的app.config时，ConfigurationErrorsException

Question

I'm building a WinForms application in C# / VS2010 / .Net4.0. My development machine is running Windows 8.1 64 bit. The application makes extensive use of app.config (user scope) to store settings. These include certain product registration details so the whole file has been encrypted using RSAProtectedConfigurationProvider. The application has an initial run (launched by the installer) in which initial settings are calculated and written before the whole thing gets encrypted. This works fine on my development machine and the application is subsequently able to read the encrypted settings successfully.

A problem arises however when I test the application in other environments (Windows 7 32/64-bit and Vista 32/64-bit under Hyper-V with .NET4.0 Client Profile installed). Here the encryption is working fine but when settings are subsequently accessed a ConfigurationErrorsException is thrown by System.Configuration.BaseConfigurationRecord.GetSectionRecursive.

I realise that the RSA encryption keys are local to an individual machine / user so that encrypted app.config files can't "travel" to other systems but here the initial encrypting is being done on the same (virtual) machine and in the same user context as is subsequently used to read the settings.

I've tried running an unencrypted version in these other test environments and everything works fine but I do need to sort this out with an encrypted version.

One thing I notice is that, while my test VMs use the .NET Framework 4 Client Profile (via the web installer), my Windows 8.1 build system has something called the ".NET Framework 4 Multi-Targeting Pack" installed. One theory I have therefore is that there is some discrepancy here but you would think that, if the encryption works, then unencryption in the same environment should work as well.

Any ideas most welcome.

Answer 1

I found that if I changed the namespace of the application, this error would pop up (I guess it corrupted the config file). Since the settings are copied to your %AppData% folder, I just changed the version of the application and did a rebuild. The error went away.