The recent update to Chrome 80 has impacted a number of users with UChat and Conga.

The issue is the default enablement of SameSite cookies. For reference, here is the article regarding Salesforce and SameSite cookies.

 To resolve the issue for either tool, follow these steps in your Chrome browser.

•  Type chrome://flags/ and hit enter. This will will take you to the 'Experiments' listing: https://www.screencast.com/t/Kdlo1MePeM.

• Type 'SameSite' into the search bar above. You will see three options: https://www.screencast.com/t/sDMyLyL8y. To use Mail Merge with Chrome 80, please disable SameSite by default cookies and Cookies without SameSite must be secure.