You’re repeatedly prompted for Exchange credentials after you sign in to Lync
- You receive a message in Lync that says it cannot connect to Exchange.
- You're repeatedly prompted to provide a user name and a password to connect to Exchange.
- You may also receive the following message: Credentials are required
- Calendar and Free/Busy information from Outlook
- Exchange Web Services (EWS)
- Response Group Service
- Address Book Service
Solutions for Lync users
- Start Internet Explorer.
- On the Tools menu, click Internet Options, click Connections, and then click LAN Settings.
- Make sure that the Automatically detect settings option is selected. If your organization requires you to enter specific information for the proxy server or an automatic configuration script, contact your network administrator.
- Restart both Internet Explorer and Lync to check whether the problem is resolved. If the problem persists, go on to the next section.
Lync can’t connect to Outlook or EWSIf Lync doesn't integrate automatically with Outlook, Lync prompts you for credentials before it lets you connect to Outlook to retrieve Calendar and Free/Busy information. If you are prompted repeatedly after you enter your credentials, see the following Microsoft Knowledge Base article:
Solutions for Lync administrators
Lync can’t connect to Outlook or EWSIf the Exchange server or EWS is unavailable, this causes Lync to continuously prompt for credentials because it can't contact Exchange for authentication. To resolve this issue, verify that Outlook has connectivity to the mailbox. If Outlook can't connect to Exchange, troubleshoot the issue as an Exchange connectivity issue. For more information, see the following Microsoft Knowledge Base article:
Ports 443, 5060, and 5061 must be open on the firewall and on proxy servers to let traffic pass freely. For more information about firewall or proxy issues in an Office 365 environment, see the following Microsoft Knowledge Base article:
Still need help? Go to Microsoft Community.
Article ID: 2298541 - Last Review: 12/16/2016 09:56:00 - Revision: 42.0
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