We have just installed a Dec 2017 CU on our SharePoint 2013 on-prem farm and after everything was installed our users Arent able to search for items.

All the services are working, crawl is working but it looks like it is now running for 23 hours. Previously our incremental crawls were done in 10-15 minutes...

Did we do something wrong or do the CU updates reset the search index?

EDIT: Everything is working as it was before except that all the content sources are crawling for over 20 hours now. enter image description here

And now IS worker process and SharePoint search component are fighting for CPU both of them go as high as 80% CPU usage, then the other process takes over and that is making our Servers be stuck in 100% CPU.

  • As already answered by others, a CU does not reset the index. You hit another problem. Could you please have a look at the "Crawl Log"? Can you see any progress there? Or is it completely stuck?
    – MHeld
    Commented Mar 8, 2018 at 8:31
  • Please look in "Crawl History" tab. This shows the data from the actual crawl. Refresh this page for some minutes and have a look if things change. Also have a look at the "Crawl rate" column to see if progress happens.
    – MHeld
    Commented Mar 8, 2018 at 8:49
  • Todd Klindt has a good webpage that you can refer to when looking for bugs or issues regarding SharePoint builds and CU's. SharePoint 2013 Build Numbers Commented Mar 8, 2018 at 8:52
  • This will sound very usual and not fancy but I think you should reboot your servers in the proper order. This is what I have to do when the crawler is blocked for some reason we don't know.
    – jaloplo
    Commented Mar 8, 2018 at 9:55

3 Answers 3


The December 2017 CU (KB 4011588/KB 4011593) does NOT reset the crawl index to answer your question.

In central administration enter search service application - content sources - click onto your content source - view crawl log and watch for errors in the current crawl to find the issue.

We got 2013 December CU installed and there was no problem with the crawler.


I didn't get that experience installing other CU's for different SharePoint versions. Anyway, you should check what is involved with Dec 2017 CU and see if there is something that reset the index. Look at this page to read the description for the CU: December 12, 2017, cumulative update for SharePoint Server 2013 (KB4011593) I couldn't find anything that points to the behaviour you asked for.

Hope this can help you.



You need run a full crawl after patching your SharePoint 2013 farm by in stalling a Cumulative Update .

The best practices is stop crawl all instance before patching CU because if a crawl is triggered by schedule which occurs during the installation, the search application may crash or lead to inadvertent results. In worst case, you might end up rebuilding the entire search application . See the below blog for detail explanation :


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