How to troubleshoot sign-in issues in Skype for Business Online

Applies to: Skype for Business Online


This guide should be used to help troubleshoot and diagnose Skype for Business Online (formerly Lync Online) sign-in and authentication issues. If Skype for Business Online users are receiving a specific error message, see the Skype for Business Online sign-in error messages table in the “More Information” section for the best recommended strategy.


The "Skype for Business Online Sign-In Guided Walkthroughs" help with identifying and resolving the main causes of sign-in issues. Before you read any further in this article or contact Technical Support, you should consult one of the following guided walkthroughs. To do this, click the appropriate link:Generally, Skype for Business Online sign-in problems can be broken up into four categories:
Category Issue Possible causes
Computer or Lync client issues These issues typically occur for a specific user or for a small group of users who have similarly configured computers or devices. Out-of-date client version, missing operating system or product hotfix, out-of-sync computer clock, incorrect cached credentials
Authentication and provisioning issues These issues typically occur for specific kinds of users (for example, federated users or users who are on a specific domain) or for a specific user who may not be entering his or her sign-in address or password correctly. Incorrect password or sign-in address, unlicensed user, Active Directory Federation Services (AD FS) not working correctly
Networking issues These problems can affect large groups of users at a specific site or network location. They can also affect users who have a specific domain. Domain Name System (DNS) for AutoDiscover not set up, proxy or firewall exceptions
Service-related issues Typically, during service-related issues, all users in a tenant are affected, but not always. Service-related issues can affect certain kinds of users (for example, users in a specific geographic region or users on a specific Lync server). Skype for Business Online service down, tenant subscription expired, Azure AD Authentication service down
If the guided walkthrough doesn’t resolve the sign-in issue, review the table in the following section for explanations and common resolutions to each error message. Additional resources for specific sign-in related issues are also listed later in this article.


Skype for Business Online sign-in error messages

After you scope the problem by using the table that appears in the "Procedure" section, use either the Error message or Type column in the following table to narrow the troubleshooting steps.
Error message Cause Type Resolution
The server is temporarily unavailable.
We're having trouble connecting to the server. If this continues, please contact your support team.
No DNS record found, or Lync server isn't responding. Network Admins: Verify the Lync AutoDiscover DNS records.

Lync users: Manually configure the Lync client as a temporary workaround. *
Lync couldn’t find a Lync Server for There might be an issue with the Domain Name System (DNS) configuration for your domain.
No DNS record. AutoDiscover fails. Network Lync admins: Verify the Lync AutoDiscover DNS records.

Lync users: Manually configure the Lync client as a temporary workaround. *
You may have entered your sign-in address, user name, or password incorrectly, or the authentication service may be incompatible with this version of the program.
Wrong version of the Lync 2010 or Lync 2013 client. Client Verify that the Lync client is up to date and that the credentials are entered correctly. *
To sign in, additional software is required. Download and install now?
The Microsoft Online Services Sign-In Assistant isn't installed on the computer that has Lync 2010 installed. Client Run Office 365 Desktop Setup, or install the latest version of the Microsoft Online Services Sign-In Assistant. *
Cannot sign in to Lync because your computer clock is not set correctly. To check your computer clock settings, open Date and Time in the Control Panel.
The time or date is set incorrectly on the device. Client The system time or date is more than five minutes off from the time or date of the Lync server. *
There was a problem acquiring a personal certificate required to sign in. If the problem continues, please contact your support team.
Cached certificate or credentials are expired or corrupted. Client Clear cached credentials and certificates. Flush DNS. *
address was not found.
User isn't licensed for Skype for Business Online. Authentication Verify that the user is licensed for Skype for Business Online. Verify that the sign-in address (SIP) is entered correctly. *
The username, password or domain appears to be incorrect.
Wrong user name, sign-in address, or password Authentication Verify that the SIP is correct. Check for a disjointed SIP or UPN scenario.

Note Apostrophes (') aren’t supported in a SIP address.

For more information about unsupported characters, see the "Directory object and attribute preparation" section of the following Microsoft website: Prepare to provision users through directory synchronization to Office 365.
The server is not responding or cannot be reached. Sign-in may be delayed while we retry the connection.
Can't contact the authentication service. AD FS 2.0 or Azure AD isn't available. Authentication Lync admins: Verify AD FS capabilities.
There was a problem verifying the certificate from the server. Sign-in may be delayed while we retry the connection.
Can't verify the certificate chain from the AD FS 2.0 server. Authentication Lync admins: Verify that clients have trusted root certification authority (CA) installed.
Note The resolutions that are marked with an asterisk (*) are included in the guided walkthrough.

Skype for Business Online sign-in resources

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