HTTP 503 : Service Unavailable

Question

I have an MVC application, that perfectly works locally. Though, after uploading it to my host's server, the domain now returns "http 503" error ; I re-published the project from within vs many times but the problem persists.

One person in another question said it's a crash problem, though how since my app is working ?

After debugging, I got the output and here it is :

'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Web\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.ApplicationServices\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.ApplicationServices.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: Domain 2): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Web\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.ApplicationServices\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.ApplicationServices.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Caching\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Runtime.Caching.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Caching\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Runtime.Caching.dll'. Symbols loaded.
A first chance exception of type 'System.UnauthorizedAccessException' occurred in mscorlib.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.Build.Utilities.v4.0\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.Build.Utilities.v4.0.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.Build.Utilities.v4.0\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.Build.Utilities.v4.0.dll'. Symbols loaded.
A first chance exception of type 'System.Globalization.CultureNotFoundException' occurred in mscorlib.dll
A first chance exception of type 'System.Security.SecurityException' occurred in mscorlib.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.JScript\v4.0_10.0.0.0__b03f5f7f11d50a3a\Microsoft.JScript.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.CSharp\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.CSharp.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.Services\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.Services.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.EnterpriseServices.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.IdentityModel\v4.0_4.0.0.0__b77a5c561934e089\System.IdentityModel.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Serialization\v4.0_4.0.0.0__b77a5c561934e089\System.Runtime.Serialization.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Activation\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Activation.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Web\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Web.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Activities\v4.0_4.0.0.0__31bf3856ad364e35\System.Activities.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Activities\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Activities.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.WorkflowServices\v4.0_4.0.0.0__31bf3856ad364e35\System.WorkflowServices.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.Extensions\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.Extensions.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.DataSetExtensions\v4.0_4.0.0.0__b77a5c561934e089\System.Data.DataSetExtensions.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml.Linq\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.Linq.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ComponentModel.DataAnnotations\v4.0_4.0.0.0__31bf3856ad364e35\System.ComponentModel.DataAnnotations.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.DynamicData\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.DynamicData.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\2982373d\e9af3651_2356d001\Antlr3.Runtime.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\432d1386\2fd0ecf8_9a71d001\BytsNBytes.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\1ef4f0eb\63b1025d_0f6fd001\EntityFramework.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\663b60c3\0860055d_0f6fd001\EntityFramework.SqlServer.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\c4d82047\23cd0856_2356d001\Microsoft.AspNet.Identity.Core.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\2df2459a\77b73356_2356d001\Microsoft.AspNet.Identity.EntityFramework.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\39a24ccf\a7a42056_2356d001\Microsoft.AspNet.Identity.Owin.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\395e37e1\cba15e56_2356d001\Microsoft.Owin.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\7256d552\a9db7856_2356d001\Microsoft.Owin.Host.SystemWeb.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\631df137\cdd8b656_2356d001\Microsoft.Owin.Security.Cookies.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\660764ab\2db39056_2356d001\Microsoft.Owin.Security.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\04a05fba\5728a656_2356d001\Microsoft.Owin.Security.Facebook.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\0f1eb96d\53e72657_2356d001\Microsoft.Owin.Security.Google.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\02319735\f30c4d57_2356d001\Microsoft.Owin.Security.MicrosoftAccount.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\bb7f228b\9debc956_2356d001\Microsoft.Owin.Security.OAuth.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\8308f0ae\7d5c3c57_2356d001\Microsoft.Owin.Security.Twitter.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.Web.Infrastructure\v4.0_1.0.0.0__31bf3856ad364e35\Microsoft.Web.Infrastructure.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\59b1a30b\49d5dc50_2356d001\Newtonsoft.Json.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\b89a07dd\ed674456_2356d001\Owin.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\74daad53\c1dae04f_2356d001\System.Web.Helpers.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\0be1ebdb\c93e4450_2356d001\System.Web.Mvc.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\a44139a0\bfa3884f_2356d001\System.Web.Optimization.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\d406d2b5\e0c53f4f_2356d001\System.Web.Razor.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\d31b065d\759fe54f_2356d001\System.Web.WebPages.Deployment.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\7c9c6215\2964ea4f_2356d001\System.Web.WebPages.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\46c5e003\83c6ec4f_2356d001\System.Web.WebPages.Razor.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\assembly\dl3\be087d70\89d55c51_2356d001\WebGrease.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.VisualStudio.Web.PageInspector.Loader\v4.0_1.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Web.PageInspector.Loader.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.WebPages.Deployment\v4.0_2.0.0.0__31bf3856ad364e35\System.Web.WebPages.Deployment.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xaml\v4.0_4.0.0.0__b77a5c561934e089\System.Xaml.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.VisualStudio.Web.PageInspector.Runtime\v4.0_2.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Web.PageInspector.Runtime.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.VisualStudio.Web.PageInspector.Tracing\v4.0_2.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Web.PageInspector.Tracing.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.RegularExpressions\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.RegularExpressions.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: DefaultDomain): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.RegularExpressions\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.RegularExpressions.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.EnterpriseServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.EnterpriseServices.Wrapper.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.Services.Design\v4.0_4.0.0.0__b77a5c561934e089\System.Data.Services.Design.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\App_global.asax.qiwhtxw_.dll'. 
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel.Internals\v4.0_4.0.0.0__31bf3856ad364e35\System.ServiceModel.Internals.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Workflow.ComponentModel\v4.0_4.0.0.0__31bf3856ad364e35\System.Workflow.ComponentModel.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Workflow.Activities\v4.0_4.0.0.0__31bf3856ad364e35\System.Workflow.Activities.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Workflow.Runtime\v4.0_4.0.0.0__31bf3856ad364e35\System.Workflow.Runtime.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.Linq\v4.0_4.0.0.0__b77a5c561934e089\System.Data.Linq.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.SqlXml\v4.0_4.0.0.0__b77a5c561934e089\System.Data.SqlXml.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Transactions\v4.0_4.0.0.0__b77a5c561934e089\System.Transactions.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xaml.Hosting\v4.0_4.0.0.0__31bf3856ad364e35\System.Xaml.Hosting.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Net.Http\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Net.Http.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\Microsoft.VisualBasic.Activities.Compiler\v4.0_10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualBasic.Activities.Compiler.dll'. Cannot find or open the PDB file.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.DurableInstancing\v4.0_4.0.0.0__31bf3856ad364e35\System.Runtime.DurableInstancing.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Security\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Security.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\SMDiagnostics\v4.0_4.0.0.0__b77a5c561934e089\SMDiagnostics.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.DataVisualization\v4.0_4.0.0.0__31bf3856ad364e35\System.Web.DataVisualization.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.Build.Framework\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.Build.Framework.dll'. Symbols loaded.
A first chance exception of type 'System.Web.HttpException' occurred in System.Web.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'Anonymously Hosted DynamicMethods Assembly'. 
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Dynamic\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Dynamic.dll'. Symbols loaded.
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'System.NullReferenceException' occurred in BytsNBytes.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Numerics\v4.0_4.0.0.0__b77a5c561934e089\System.Numerics.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data.OracleClient\v4.0_4.0.0.0__b77a5c561934e089\System.Data.OracleClient.dll'. Symbols loaded.
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.SqlServer.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.SqlServer.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'EntityFrameworkDynamicProxies-EntityFramework'. 
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.dll
A first chance exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.SqlServer.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'EntityFrameworkDynamicProxies-BytsNBytes'. 
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.Mobile\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Web.Mobile.dll'. Symbols loaded.
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\App_Web_n2bonnra.dll'. 
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\App_Web_erouy4nj.dll'. 
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Users\User0\AppData\Local\Temp\Temporary ASP.NET Files\root\6ae02a6d\6ab4d59c\App_Web_2ktmhc3s.dll'. 
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll
'iisexpress.exe' (CLR v4.0.30319: /LM/W3SVC/9/ROOT-1-130729680602128906): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.VisualStudio.Web.PageInspector.HtmlParser\v4.0_2.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Web.PageInspector.HtmlParser.dll'. Cannot find or open the PDB file.

is it a problem from the host's company ? note the exception :cannot find or open pdb file..these are system dlls !

Please tell me how such an error can originate, while the app actually works ?

Hence, an older version also worked perfectly before (even on the host's machine), yet now after publishing the older version, it doesn't work.

Answer 1

尝试运行“ aspnet_regiis.exe”（在管理员模式下打开命令提示符，然后转到C：\\ Windows \\ Microsoft.NET \\ Framework \\ v4.0.30319（如果是32位PC）C：\\ Windows \\ Microsoft.NET \\ Framework64 \\ v4.0.30319（如果是64位PC），然后键入aspnet_regiis.exe -i并按Enter键

Answer 2

The technical support of the host's company just replied. They fixed the site via restarting the app pool.

The reason was that the mvc project (when running) is consuming too much memory (ie which is true since I have portions of code which process thousands of instances).

When that happens and the consumption exceeds the site's memory, the project is recycled automatically by IIS ; thus the problem occurs, and the application pool must be restarted in order for the site to work again.

Please, add this to your list of reasons, why "http 503" might occur. It might -as in my case- root back to the hosting plan & the site's memory.

https://besthostingforasp.net/asp-net-service-unavailable-503-error-using-shared-windows-server/