When users create a meeting on the Calendar tab of Microsoft Teams to mailboxes that are hosted in Microsoft Exchange Server 2019 or Exchange Server 2016, the REST calls from Microsoft Teams exceed the 2K default IIS limit of the maxQueryStringLength property. After the Microsoft Teams users join the meeting, you may see that many "1309" events about maxQueryStringLength exceptions are logged in the Application log. Additionally, the presence information is not accurate in Microsoft Teams.
This issue occurs because there's no value set for maxQueryStringLength, so IIS falls back to the 2k default limit.
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 8 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 19 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Learn about the terminology that Microsoft uses to describe software updates.