Term Store and Search index - a rocky relationship since 2013

Ultra short version:

Question: When I update a term in the Term Store, how long will I have to wait until the Search Index has picked up that change?

Answer: Either forever or until you have updated every item using that term or triggered a reindex of those lists that contains that term. Script available at the end of this post.

Many SharePoint admins and developers are not really familiar with the inner workings of the Term Store, Managed Metadata fields. and Search. In most cases that knowledge isn't really required but when answering the question above, it is very much required.

In this case I have a Finance term in the Tenant Term Store. The default language for the Term Store is English but the Finance term has been translated to Danish as well.

This mean that a user will see the term in the Danish "version" if they have selected that language as the User Interface language in the M365 settings

Term Store - Finance

The value for the Finance term when seen by a danish user

So, what happens if the CEO of the company decides that "Finance" sounds old fashioned and should be updated to "fiscal affairs" department?

We can update the text value (aka the term label) to "Fiscal affairs", but remember that there is a Danish Translation as well. That translation must be updated to a suitable label as well.

Term Store - Finance

Once the labels have been update we would expect the values in the lists and libraries to be updated, but you must be patient. That update job only run every 24h.

Once the values have been updated and every "Finance" now is "Fiscal affairs" we would expect that value to show up in Search as well, right?

WRONG!!

The Search Index in SharePoint Online is only updated when any of a number of triggers are activated. Only Microsoft know the complete list of triggers, but these are commonly known:

• When the item/document is created/updated

• When the List/Library receives a reindex request

• When the Site Collection receives a reindex request

Updating a Term label does not activate any of these triggers and therefore the Search Index will not be updated!!!

Note: the concept from SharePoint On Premises of a "full crawl" does not exist in SharePoint Online.

There are scripts available that will enable you to reindex your entire tenant, but it should only be used VERY sparsely. And not in this case.

I have added a script to PnP Script Samples that will find the lists and libraries where this specific Term is used and request a reindex of only those list/libraries, minimizing the impact of the tenant: Reindex Search index for lists where a specific term is used (when you have renamed the term) | PnP Samples

I will recommend you start by just getting the number of lists affected. If the term is used in a huge number of lists, you might consider running the script outside business hours as it might use a lot of ressource units.