Collab365 Q&A


Arg, once again we are getting burned by a Sharepoint provider hosted app that we had contractors write for us.

Any experts? We have this app that essentially does SSO into our student information system. Now we’re getting “an unexpected error has occurred. Please try again by launching the app installed on your site.”

Previously when we’ve seen similar error messages, it’s been an expired SSL certificate somewhere, but I’ve triple checked and I don’t see any expired.

ULS logs don’t have any red flags that I can see.

To make matters EXTRA complicated, we were having these symptoms last week in our dev/test environments, but prod was fine. Over the weekend the city lost power and our data center went down hard. No prod has the same answer. Not totally sure if they are related. Our developers claim to have no changed anything in 7 months with that app.

Not sure where to keep looking with SP and IIS logs not offering any clues.


This is Sharepoint 2013 on-prem.


Oddly enough this turned out to be a network issue!  Communication for web traffic was not working between the hosted app server and the SP web server.  (But only in one direction, and not for ICMP)

Weird, as there were no firewalls or anything between then, it was resolved with a vmotion.  Turns out that a hard power down of your data center with a power loss is a bad thing!  Who knew.


Thanks for the screen shots. Without being able to debug, my first instinct is that your client secret has expired. Here is a link about this issue.

let me know if i can be of anymore help.


Sure,  here is what it looks like when trying to access it “normally”.

To try to make it a little easier to read, this is if we hit the URL directly.  TBH, we would normally never try to access it this way, so I can’t say what normal behaviour would look like.


I have passed your other comments along to our in-house developers.  (We have good .net people, but with very limited experience with anything that ties into SharePoint).

The solution went live in October 2014, so it’s definitely older than 2.

Thanks for the reply!


Can you post a screen shot? This error is 99% an ASP.NET error, which means it wont show up in your ULS… This is the standard generic error in a Visual Studio Project Template. Did the original developers have an error log for tracking down these errors?

If not, you’ll need to try and remote-debug the application using Visual Studio to see what the error is. Or try and debug in your dev/test environments to further narrow down the error. Unfortunately if the original developer/contractor didn’t add error logging, this is your best bet.

Also, how old is this application? Client IDs and Secrets last for 2 years (some less, depending). It is possible your clientID and clientsecret (from your application registration in SharePoint) has expired and your application can no longer authenticate. In this scenario, you’ll need to regenerate a client ID and secret (/_layouts/15/appregnew.aspx), take those keys and add them to the Application Manifest and deploy the .app file, as well as update the web.config in your provider hosted app to use those new keys.