PHP weird session data in file, cannot unserialize

I need to share sessions between subdomain but my sessions are stored in weird format. For example if ill compare same session data (from session file) from different servers i see that in first case data are stored correctly but not in second one.

First server session string:

TEST_VAR|s:10:"TEST VALUE";

Second server session string:

NUnNmu-NLaO2lP-1J_LVRdJm5cPH54dlnDN1W1GaHXrebf3hl_clOl3xeoZlvHsj

I'm using same code to generate sessions, where is the problem? Anyone know whats wrong? How can i decode this weird开发者_如何转开发 string? session_decode() can't handle it.

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This might help: PHP / Drupal, Session Storage and encryption

If not, check the php.ini/phpinfo() on both servers and see if there are any differences in the session-related configuration.