I have a brand new setup with Server 2012R2 Std and Exchange 2013 CU9.  The Exchange is on one server (MBX and CA).  I used the CU9 download to install, then applied my code.  Brand new Exchange environment in a brand new AD environment... NO UPGRADES/MIGRATIONS!  

After i got everything setup, within ECP, I switched mail to start flowing and to check flow i then logged in as a user, upon logging in i get a "Something went Wrong" page with no real information.  The only place i could find ANYTHING to elude to a problem is in Event Viewer.  Below is a few of the errors i find:

Event code: 3008 
Event message: A configuration error has occurred. 
Event time: 7/18/2015 6:55:49 PM 
Event time (UTC): 7/18/2015 11:55:49 PM 
Event ID: 41e883c33fca495d94c7429db0d376f4 
Event sequence: 1 
Event occurrence: 1 
Event detail code: 0 

Application information: 
    Application domain: /LM/W3SVC/2/ROOT/owa-3-130817373489241270 
    Trust level: Full 
    Application Virtual Path: /owa 
    Application Path: C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\owa\ 
    Machine name: EX13 

Process information: 
    Process ID: 2836 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\SYSTEM 

Exception information: 
    Exception type: ConfigurationErrorsException 
    Exception message: Could not load file or assembly 'Microsoft.CobaltCore, Version=16.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)
   at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory()
   at System.Web.Configuration.AssemblyInfo.get_AssemblyInternal()
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig)
   at System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded)
   at System.Web.Compilation.BuildManager.ExecutePreAppStart()
   at System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException)

Could not load file or assembly 'Microsoft.CobaltCore, Version=16.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)

Could not load file or assembly 'Microsoft.CobaltCore' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))



Request information: 
    Request URL: https://localhost:444/owa/proxylogon.owa 
    Request path: /owa/proxylogon.owa 
    User host address: ::1 
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: NT AUTHORITY\SYSTEM 

Thread information: 
    Thread ID: 16 
    Thread account name: NT AUTHORITY\SYSTEM 
    Is impersonating: False 
    Stack trace:    at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)
   at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory()
   at System.Web.Configuration.AssemblyInfo.get_AssemblyInternal()
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig)
   at System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded)
   at System.Web.Compilation.BuildManager.ExecutePreAppStart()
   at System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException)


Custom event details: 

I have tried everything I can think of, but cannot login with OWA.  ALSO.. I did try to reinstall with the "/mode:upgrade" command...   But this yields the same thing.   PLEASE HELP!!!

Hi.

Check and follow.

Checklist: Perform a new installation of Exchange 2013

So.... Am I looking for anything specific here.. it's all common stuff...  I've installed Exchange 2013 a few times already in my life, so i'm familiar with the process... 

For specifics, i've followed all instructions here:  http://enterpriseit.co/microsoft-exchange/2013/install-cu5/   which i've done MANY times before.  If i missed something that you're aware of, great, then please tell me, but don't just throw a giant checklist at me please.  I'm well aware of the pre-reqs and install procedures for this product.

I have found many other references in my event viewer stating that apppools have been disabled, however, they're listed as started in IIS.  Here's an example (however there are many more):

As of now i seem to have resolved my issues...  OWA works now.

for anyone that would like to know: 

1.  run "iisreset -stop"

2.  Navigate to:  "C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files"

3.  Delete EVERYHING in this folder (I did make a full copy of the Temporary Files folder first just in case).

4.  Run "iisreset -start"

As of now i seem to have resolved my issues...  OWA works now.

for anyone that would like to know: 

1.  run "iisreset -stop"

2.  Navigate to:  "C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files"

3.  Delete EVERYHING in this folder (I did make a full copy of the Temporary Files folder first just in case).

4.  Run "iisreset -start

Thanks a lot Jeff, this also worked for me after a couple of days troubleshooting.

You are a star :)