Exception Details: System.Security.Policy.PolicyException: Required permissions cannot be acquired

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[PolicyException: Required permissions cannot be acquired.]
   System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) +7627475
   System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) +57

[FileLoadException: Could not load file or assembly 'Oracle.DataAccess, Version=2.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
   System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +43
   System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +127
   System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +142
   System.Reflection.Assembly.Load(String assemblyString) +28
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +46

[ConfigurationErrorsException: Could not load file or assembly 'Oracle.DataAccess, Version=2.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +613
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +203
   System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +105
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +178
   System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +54
   System.Web.Compilation.CodeDirectoryCompiler.GetCodeDirectoryAssembly(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories, Boolean isDirectoryAllowed) +600
   System.Web.Compilation.BuildManager.CompileCodeDirectory(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories) +125
   System.Web.Compilation.BuildManager.CompileResourcesDirectory() +31
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +304

[HttpException (0x80004005): Could not load file or assembly 'Oracle.DataAccess, Version=2.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +58
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +512
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +729

[HttpException (0x80004005): Could not load file or assembly 'Oracle.DataAccess, Version=2.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9002835
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +85
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +333

Most likely you tried it only with the built-in server of Visual Studio which doesn't keep in mind the security restraints as IIS does. you could test by hosting site in iis or create a new project in vs and copy pate code in that project. look like your assembly loaded in which profile does not have night permission to access it.

option 1: you could try to set the trust level in your web.conifg fil to resolve the issue.

<system.web>
    <securityPolicy>
        <trust level="Full" />
    </securityPolicy>

...
</system.web>

option 2: find the oracle assembly and grant the permissions for the assemblies

option 3: Open the properties of the DLL in Windows Explorer. It's likely marked as blocked because it was downloaded from the internet. Go to properties & click the "unblock" button and the problem may be solved.

reference link:

https://social.technet.microsoft.com/Forums/lync/en-US/56004b3e-487d-472c-b644-72cee8537ea7/loading-dll-from-network-fails-caspol-doesnt-fix-problem?forum=winserverpowershell