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You are continuously prompted for credentials after you sign in to Lync OnlineArticle ID: 2298541 - View products that this article applies to. Not sure what release of Office 365 you're using? Go to the following Microsoft website: Am I using Office 365 after the service upgrade?
(http://office.microsoft.com/redir/HA103982331.aspx)
On This PagePROBLEM
SOLUTIONThis issue occurs for multiple reasons, and in certain scenarios, it is the expected behavior. Lync generally prompts you for credentials only after you're signed in and when it must connect to an external service such as the Microsoft Exchange Free/Busy service or the Exchange Calendar service. If Lync continues to prompt you for credentials after it has done this several times, there's probably an issue with Outlook or with the Exchange services. Solutions for Lync usersCollapse this image ![]()
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:2436962 If Lync doesn't automatically connect to EWS, Lync prompts you for credentials before it lets you access the EWS URLs. If you are still prompted after you enter your credentials, see the following Microsoft Knowledge Base article:
(http://support.microsoft.com/kb/2436962/
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"There was a problem connecting to Microsoft Office Outlook" error when you sign in to Lync Online 2787614
(http://support.microsoft.com/kb/2787614/
)
Conversation history, contact cards, Free/Busy, and Out of Office information are unavailable when Lync fails to connect to Exchange Collapse this image ![]() Solutions for Lync administratorsCollapse this image ![]() 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:2787614 If a firewall or a proxy is preventing Lync from connecting to EWS, you may experience symptoms such as repeated credential requests, stale ABS, and intermittent Free/Busy presence issues.
(http://support.microsoft.com/kb/2787614/
)
Conversation history, contact cards, Free/Busy, and Out of Office information are unavailable when Lync fails to connect to ExchangePorts 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: 2409256
(http://support.microsoft.com/kb/2409256/
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You can't connect to Lync Online, or certain features don't work, because an on-premises firewall blocks the connection Collapse this image ![]() PropertiesArticle ID: 2298541 - Last Review: July 31, 2013 - Revision: 35.0 Applies to
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