Login failure in Lync 2010 or Office Communicator
While login on Office Communicator 2007/R2/Lync 2010 client in Lync Server 2010
enviornment you might face login failure issue with the below error messages.
Lync was unable to sign in.
Please verify your logon credentials and try again. If problem continues, please
contact your support team.
Cannot sign in to Communications
Service. You may have entered your sign-in name, username, or password incorrectly,
or the authentication service may be incompatible with this version of the program.
If your sign in information is correct and the problem persists, please contact
your system administrator.
This issue happens on Window
XP SP3 and Windows Vista Machines.
There are two way you are
resolve this issue. Applying Group Policy on client machine or setting all Lync
server including Lync Edge Servers with NTLM without 128 bit encryption.
Resolution 1 (on
Click on Start > Run,
type there gpedit.msc and press enter.
It will open below screen.
Now in the right pane expand Computer Configuration
> Windows Settings > Security Settings > Local Policies > Security
Double click on Network Security
: “Minimum Session Security for NTLM SSP based
(Including secure RPC) clients” and “Network
Security : Minimum Session Security for NTLM SSP based (Including secure RPC) servers”
one by one. It will open the screen similar to the below depending upon the version
of your Windows Operating system..
By default the “Required 128-bit encryption”
box would be showing unchecked. Check this box and now the screen will look like
Click on “OK” and then restart your computer.
After machine is restarted you should be able to login to Lync 2010 client.
In case you face any issues please contact firstname.lastname@example.org.
Resolution 2 (Server
Side): If you do not want to
apply group policy to all your Domain joined machine then you can you can use below
steps on all your Lync 2010 Server and Lync Edge Server.
Login on all Lync Servers
one by one.
Follow the steps 1 to 4 mentioned above in the
Resolution 1 (on client machine).
Now uncheck Require 128
Bit encryption both for Network Security : “Minimum
Session Security for NTLM SSP based (Including secure RPC) clients” and
“Network Security : Minimum Session Security
for NTLM SSP based (Including secure RPC) servers”
Restart servers one by one.