I am trying to install into umbraco 7.15.4 latest cmsimport umbraco package and i get the following error:

2020-06-04 10:23:09,994 [P22408/D2/T15] ERROR umbraco.cms.businesslogic.packager.Installer - Error importing file C:\inetpub\wwwroot\mysite\App_Data\58b7568b-8c2e-47df-acf1-fb3d9b002c9b.umb System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401) at System.Web.Security.RolePrincipal..ctor(SerializationInfo info, StreamingContext context) at System.AppDomain.CreateInstanceAndUnwrap(String assemblyName, String typeName) at Umbraco.Core.Packaging.PackageBinaryInspector.ScanAssembliesForTypeReference[T](String dllPath, String[]& errorReport) at umbraco.cms.businesslogic.packager.Installer.LoadConfig(String tempDir) at umbraco.cms.businesslogic.packager.Installer.Import(String inputFile, Boolean deleteFile) 2020-06-04 10:23:09,994 [P22408/D2/T15] ERROR Umbraco.Web.WebApi.Filters.FileUploadCleanupFilterAttribute - Could not acquire actionExecutedContext.Response.Content System.NullReferenceException: Object reference not set to an instance of an object. at Umbraco.Web.WebApi.Filters.FileUploadCleanupFilterAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext) 2020-06-04 10:23:09,994 [P22408/D2/T15] ERROR Umbraco.Web.Editors.PackageInstallController - Unhandled controller exception occurred System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401) at System.Web.Security.RolePrincipal..ctor(SerializationInfo info, StreamingContext context)

Any ideas?

Regards

Ismail