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K2 Studio is not connecting to K2 server: "Open Failed: Open may only be called on a primary login"

This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice. This article is not considered official documentation for K2 software and is provided "as is" with no warranties.


K2 Studio is not connecting to the K2 server with the following message appearing: "Open Failed : Open may only be called on a primary login"


This was identified as a known issue when upgrading to K2 5.2 or 5.3 with the K2 Studio Client tools.

After upgrading to 5.2 or 5.3 you will be unable to connect from K2 Studio to the K2 server, due to invalid connection Strings.

Troubleshooting Steps

To resolve this issue validate that the K2Studio.exe.config file(C:\Program Files (x86)\K2\K2Studio) is correctly configured.

Below is the incorrect and correct configuration:

Incorrect Connection String

<add name="HostServer" connectionString="[K2HOSTCONNECTIONSTRING]" providerName="[LICENSEDPRODUCT]" />

Correct Connection String

<add name="HostServer" connectionString="Integrated=True;IsPrimaryLogin=True;Authenticate=True;EncryptedPassword=False;Host=k2server.com;Port=5555" providerName="K2blackpearl" />

This issue was identified on the K2 Studio Client installation and identified as a known issue in the K2 Product and will be addressed in a future release.