Resolve Cryptographic Exceptions in IIS
An IIS deployed application throwing a CryptographicException with the message System cannot find the specified file can be a perplexing issue.
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Resolve Cryptographic Exception in IIS
Situation
An IIS deployed application is throwing a CryptographicException with the message System cannot find the specified file. Not a very useful message now is it?!
Remedy
This is most likely because the Windows Cryptographic Service Provider was trying to store or load a key for a certificate in the user store, and since a profile was not available, a cryptographic context was not available. This means the Process model has the Load User Profile set to false.
⚠️ The Load User Profile setting only applies to user accounts. Service Accounts like NETWORK SERVICE and ApplicationPoolIdentity have special handling.
What exactly happens when I set Load User Profile in the IIS pool?
The user profile is loaded. This includes their cryptographic store, environment variables such as %TEMP%, and other ones.
To enable the setting
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Go to the IIS Manager
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Go to the application pool instance
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Click on Advanced settings
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Under the Process model, set Load User Profile to true
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Recycle the application pool and restart the linked web application for changes to reflect