When a Salesforce org is upgraded from Starter Edition to Professional or Enterprise Edition, Chatter and its related features including Chatter feeds, Chatter groups, and collaboration tools — may not be automatically activated. As a result, users are unable to access Chatter even though the new edition supports it. This occurs because Chatter Org Settings must be explicitly enabled after an edition upgrade and are not carried over automatically from Starter Edition.
Chatter and related features may not be activated automatically after changing your Salesforce edition. Salesforce Support can enable Chatter Org Settings on your behalf by submitting an internal activation request (LAP). To request this, contact Salesforce Support and provide the following information:
Similar issues : 'Switch to Salesforce Classic' Not Available after Upgrade from Essentials Edition
005239094

We use three kinds of cookies on our websites: required, functional, and advertising. You can choose whether functional and advertising cookies apply. Click on the different cookie categories to find out more about each category and to change the default settings.
Privacy Statement
Required cookies are necessary for basic website functionality. Some examples include: session cookies needed to transmit the website, authentication cookies, and security cookies.
Functional cookies enhance functions, performance, and services on the website. Some examples include: cookies used to analyze site traffic, cookies used for market research, and cookies used to display advertising that is not directed to a particular individual.
Advertising cookies track activity across websites in order to understand a viewer’s interests, and direct them specific marketing. Some examples include: cookies used for remarketing, or interest-based advertising.