cacti issues after update.

[romstation]

Hello Everyone, i'm new on cacti forum,

I upgraded my cacti version 0.8.8 to version 1.1.19 but now i have this error in log menu

2018-06-21 18:58:08 - CMDPHP PHP ERROR WARNING Backtrace: (/clog.php: 27 include)(/include/auth.php: 27 include)(/include/global.php: 322 include_once)(/include/global_arrays.php: 1142 date)(CactiErrorHandler)(/lib/functions.php: 4416 cacti_debug_backtrace)
2018-06-21 18:58:08 - ERROR PHP : date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Africa/Brazzaville' for 'WAT/1.0/no DST' instead in file: /usr/share/cacti/include/global_arrays.php on line: 1142
2018-06-21 18:58:08 - CMDPHP PHP ERROR WARNING Backtrace: (/clog.php: 27 include)(/include/auth.php: 27 include)(/include/global.php: 322 include_once)(/include/global_arrays.php: 1142 strtotime)(CactiErrorHandler)(/lib/functions.php: 4416 cacti_debug_backtrace)
2018-06-21 18:58:08 - ERROR PHP : strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Africa/Brazzaville' for 'WAT/1.0/no DST' instead in file: /usr/share/cacti/include/global_arrays.php on line: 1142

what can i do to solve this error ???
Thks for your support.

[cigamit]

Edit your PHP.ini and set the timezone parameter to a proper timezone.

[romstation]

Thanks for your reaction.

I applied the changes as you recommended and now the errors are no more displayed. But i have this warning

POLLER: Poller[1] WARNING: Invalid Response(s), Errors[1] Device[My_device_hostname] Graphs[] DS[1275]

what does it means ?

[netniV]

That line looks strange because there is a datasource but no graph associated to it (or at least no name).

Invalid response can mean that either the device took too long to respond, has the wrong hostname, or is not configured to respond to SNMP (assumng that the datasource is an SNMP datasource).

[romstation]

curiously, I have all the graphs associated to this equipment in the graph menu.