The response from /EPiServer/cms/Stores/notification/ is:

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Do you have any logs from server? which can give me any clue to figure out what is going on? This response seems resulted from a wrong encoding. The server log can tell you more in case of 500 errors. 

I found the problem. It was related to code I was executing in an ActionFilter.

<p>@Anders: Do you recall what the issue was? I'm currently experiencing the same.</p>

@Mathias Unfourtuneatly I do not remember exactly, but I think that is was related to code i had in a class inheriting from ActionFilterAttribute that messed up the response. I was trying to remove the header value "X-Frame-Options" for request originating from a specific network.

Ok, seems like my issue is different. System.Web.HttpContext.Current is returning null when requesting /EPiServer/cms/Stores/notification/. This is since updating EPi from 9.5 to 10.1.

<p>Hi mathias,</p> <p></p> <p>i just upgraded to 10.1 as well and i get this error as well..</p> <p></p> <p>when loggin into the CMS i get this popup. Nothing in the code was changed only the upgrade. So why is this now complaining?&nbsp;</p> <p></p> <p><img src="https://s1.postimg.org/6d5flz9vz/Capture.png" width="640" alt="Error" height="646" /></p> <p></p> <p></p>

Hi Vishal!

We reverted our upgrade (for reasons) and put it back in the backlog for now so I'm afraid I didn't get to the bottom of this 

I see...

i wonder what the Stores/Notification does, and how can i debug that a bit better to figure out what is causing this. 

THe thing is, that if i just ignore this error, the CMS otherwise works perfectly. So i dont experience any strange things, but still its annoying when you get this going to the CMS.

Hi Visual, 

Can you take the screen shot of full exception message and post it here. The above you pasted show that it is a method not implementaion exception. If you can find which method is throwing this, that will help. 

At high level it seems you are using some User/membership provider which doesn't have some method. It could be possible that notification Store is trying to resolve the full username but the relevant provider doesn't implement some specific methods. 

Hi Vishal,

In your screenshot I can see from the stacktrace that there is code in nl.hro.CMProviders.CMMembershipProvider.FindUsersByName that throws NotImplementedException.

This is not EpiServer code throwing this exception. I suggest that you implement that FindUsersByName method to prevent this error from happening.

Hi Khurram,

below is the full exception.

And yes. I we have for production the custom provider implemented. Which was there in EPi 9 as well. I only got that dll from the client because we didnt implement that provider. 

I dont think the interface changed in EPI forcing to implement that method and we didnt change anything. ONly upgraded. 

ALso this provider only is active on the production environment. On local dev we use the normal sql provider, but still get this error. 

Do you have the membership provider set to MultiplexingMembershipProvider?

Yes Aniket, its like so..

  <membership defaultProvider="MultiplexingMembershipProvider" userIsOnlineTimeWindow="10" hashAlgorithmType="HMACSHA512">
      <providers>
        <clear />
        <add name="MultiplexingMembershipProvider" type="EPiServer.Security.MultiplexingMembershipProvider, EPiServer.Framework" provider1="SqlServerMembershipProvider" provider2="WindowsMembershipProvider" provider3="CMMembershipProvider" />
        <add name="WindowsMembershipProvider" type="EPiServer.Security.WindowsMembershipProvider, EPiServer" deletePrefix="BUILTIN\" searchByEmail="true" />
        <add name="SqlServerMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="EPiServerDB" enablePasswordRetrieval="false" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="5" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="EPiServerSample" />
        <add name="CMMembershipProvider" type="nl.hro.CMProviders.CMMembershipProviderRead" applicationName="Internet" serviceUrl="http://cmclientservice.hro.nl/cmclientservice.svc" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" passwordFormat="Hashed" maxInvalidPasswordAttempts="5" passwordAttemptWindow="10" />
      </providers>
    </membership>

Try changing the defaultProvider to SQLMembershipProvider instead.