FreePBX 2.10 retrieve_conf error

I had installed Asterisk 1.6.2 and FreePBX 2.9… and everything was running fine. After I upgraded to Asterisk 1.8.11 and FreePBX 2.10 the system returns this message when I want to apply any change:

"Reload failed because retrieve_conf encountered an error: 1

exit: 1
not writable[FATAL] retreive_conf failed to get engine information and cannot configure up a softwitch with out it. Error: ERROR-UNABLE-TO-PARSE

1 error(s) occurred, you should view the notification log on the dashboard or main screen to check for more details."

So, the extensions are not able connect to asterisk.

This is what I got:

asterisk -rx 'core show version’
No such command ‘core show version’ (type ‘core show help core show version’ for other possible commands)

And these are the available options:

*CLI> core show
application applications calls channel channels
channeltype channeltypes codec codecs config
file function functions help hint
hints image switches taskprocessors translation

The Asterisk version I have installed is:

asterisk -V

Asterisk 1.8.11-cert4

I started this updating process with version 1.8.13 (which is the latest LTS version) and since I received that FreePBX error then I downgraded it to 1.8.11-cert4.

The most important thing is the extensions and trunk appear to be connected and registered, but when I want to make a call (even to the voice mail) I get this error on console (Verbose=10 & Debug=10):

== Using SIP RTP TOS bits 184
== Using SIP RTP CoS mark 5
– Incoming call: Got SIP response 405 “Method Not Allowed” back from 192.168.XXX.XXX:XXXX

I’m sorry, I forgot to thank you for that so-early reply.

what do you get when you type:

asterisk -rx ‘core show version’