[horde] Fatal Error: undefined method stdClass::write()

[balia]

hi,
I installed Horde 5.2.15 on a Debian Jessie Server.
After I try to login, I get:
HORDE: [horde] Call to undefined method stdClass::write() [pid 21206  
on line 4431 of "/usr/share/php/Horde/Imap/Client/Socket.php"]
How do I resolve this?
Thks...