If you only get the error when accessing the server for first time after an idle time or running an antivirus scan then disable the File Change Notification feature on the IIS server where StoreFront is running.
For .NET 4.0 and Lower
Find app bitness from appPool advance settings.
64 bit: To enable this hotfix, you must add the following DWORD value of 1 at the following registry key:
HKLMSoftwareMicrosoftASP.NETFCNMode
32 bit: If you are running a 32-bit process on an x64-based system, add the following DWORD value of 1 at the following registry key:
HKLMSOFTWAREWow6432NodeMicrosoftASP.NETFCNMode
For .NET 4.5 and Higher
Starting with the Microsoft .NET Framework 4.5 and later versions, FCNMode can be configured by using the httpRuntime settings as follows:
<httpRuntime fcnMode=”Disabled”/>
For more information refer to the following blogs:
ASP.NET File Change Notifications, exactly which files and directories are monitored?
ASP.NET Performance issue: Large number of application restarts due to virus scanning