Hi Pisit38,

Please check the connection string that you have set up and make sure the information is correct, credentials could be configured incorrectly.

Please follow the link below:

http://community.k2.com/t5/K2-Blackpearl-Forum-Posts/24404-Authentication-with-server-failed/td-p/85369

You can also check out this article post:

http://community.k2.com/t5/K2-blackpearl-Articles/Cached-User-Credentials-Causing-24404-Authentication-with-server/ta-p/88783

Kind Regards

Luyanda

Still not work I use K2 with .Net 

For example 

Password="d]h;psv,88"

But when I put {} 

connection string see Password="{d]h;psv,88}"

that make passwork incorrect 

Hi,

Out of curiousity, are you try to open a connection/impersonate another user via K2 APIs? I believe semicolons are reserved characters. I have seen something similar in the past when password containing semicolon (;), comma (,) and/or equal sign (=) are not supported. Perhaps, this KB might help, help.k2.com/kb002248.

Right now this problem has solved, thank you for your help