There is a problem with specific versions of memcached and the php-memcache module as can be read
here. This is the logging of memcached when logging into roundcube:
-----
<36 new auto-negotiating client connection
36: Client using the ascii protocol
<36 incr __CONNECTIONTEST__ 1
>36 NOT_FOUND
<36 get gi59ib235ih5n87rrf6v4jk955
>36 END
<36 delete gi59ib235ih5n87rrf6v4jk955 1
>36 CLIENT_ERROR bad command line format. Usage: delete
[noreply]
<36 connection closed.
-----
I tried to install a correct version according to this page (I have memcached 1.4.5 and installed php-memcache 2.2.5) but this doesn't work either. I can't seem to find the code that deletes a specific key (I am not a PHP programmer). This code probably adds a TTL of 1 to the delete somehow. I want to remove this, or set the TTL to 0 which should also work. If someone has some insight about this, please let me know. This is driving me crazy.
Jurriaan