Update (Sept 15, 9:02 AM ET): The issue is still on going and intermittent with lots of mentions on various social networks. The problem described on the Office 365 service status page still doesn’t mention the general issues with provider hosted apps but only focuses on workflows which it claims are in recovery. In related news, Azure appears to be having widespread outages today as well.
Update (Sept 14, 5:02 PM ET): The issue appears to be resolved at this time. If you are still having trouble, please leave a comment.
SP77334 - SharePoint Features - Service degradation
Service degradation - Sep 14, 2016 11:23 AM
Current Status: We're investigating system logs to determine the source of the issue.
User Impact: Users may be unable to execute SharePoint 2013 workflows. Additionally, users may be unable to view SharePoint 2010 workflows.
Scope of Impact: A few customers have reported this issue, and our analysis indicates that this issue may potentially affect any of your users attempting to execute or view SharePoint workflows.
Start Time: Monday, September 12, 2016, at 12:56 PM UTC
Next Update by: Wednesday, September 14, 2016, at 5:30 PM UTC
I’ll bet you a dollar that what they see in the system logs indicates some sort of auth failure! 😉 Today might be a good day to do work that doesn’t require SharePoint Online. Original: There seems to be a major problem with SharePoint Online today that we first observed yesterday evening. I’m seeing it here and a few customers have reported it already although the Office 365 service status dashboard currently shows no issues at the time of this writing. When you try launch Instant Consulting Practice or Instant Legal Practice you may see the following error. Note that this is our error screen, other apps will behave differently, but all apps on our tenants are currently affected.
Basically, what that means is that SharePoint is sending an empty request when you try to launch the app instead of including the values an app needs to connect to SharePoint. If you are affected by this, please open a support ticket with Microsoft. –Doug Ware