The Symptom

Users were experiencing a 5-15 second delay when saving a document to OneDrive or SharePoint, during which Word would show as “not responding”.

All machines in question use App Control for Business (WDAC).

The Cause

During the “not responding” period, Word is attempting to start the Web Client service, which is set to Manual.

svchost.exe launches, tries to load the WebClnt.dll library, but this is blocked by App Control for Business.

Word has to wait for this attempt to time out, before then giving up and saving anyway.

The Fix

Setting the Web Client service start type to Disabled prevents Word from attempting to start the service, fixing the delay.

The Diagnosis Process

Event Tracing for Windows and UIforETW strike again, along with the incredible utility of the public symbols for Office.

The process was similar to that which I documented here, where the process of saving comments in Word caused a hang. The key is to click Trace > Load Symbols to ensure we have function names in the trace.

Drilling down to the problem time area and then digging into the amount of time we spend in each function revealed that the time was being spent in davhlpr.dll!TriggerStartWebclientServiceIfNotRunning.

Well this does indeed sound like something to do with the Web Client service!

» Read the rest of this post…

I am a great admirer of the work of Bruce Dawson on Event Tracing for Windows, UIforETW and his blog posts on using ETW to track down all sorts of weird and wonderful issues.

I also found Bruce’s training videos on the subject, despite the videos knocking on the door of being a decade old, to be very useful.

I was delighted to have a recent opportunity to practise my own skills in this area, following Bruce’s lead!

The Symptom

The end user was experiencing delays of between several seconds and about half a minute when saving comments in a Word document. Choosing to Insert the comment was fine and when typing the comment, Word also behaved normally. Press Save, however, and Word’s UI would hang for somewhere between a few and 30 seconds.

Yep, sometimes half a minute for each comment being saved!

In a document that required a lot of comments, this was dramatically slowing the user’s work.