poller-wrapper.py do not working

Hello,

We have update our Linux server today and after that Observium discovery, polling do not work.

observium@observium:~$ python /opt/observium/poller-wrapper.py
PHP Fatal error:  Uncaught phpFastCache\Exceptions\phpFastCacheIOException: Path "/tmp/observium_cache/cli/Files" is not writable, please set a chmod 0777 or any writable permission and make sure to make use of an absolute path !
Additional information provided by error_get_last():
chmod(): Operation not permitted in /opt/observium/libs/phpFastCache/Core/Pool/IO/IOHelperTrait.php line 103 in /opt/observium/libs/phpFastCache/Core/Pool/IO/IOHelperTrait.php:121
Stack trace:
#0 /opt/observium/libs/phpFastCache/Drivers/Files/Driver.php(58): phpFastCache\Drivers\Files\Driver->getPath()
#1 /opt/observium/libs/phpFastCache/Drivers/Files/Driver.php(48): phpFastCache\Drivers\Files\Driver->driverCheck()
#2 /opt/observium/libs/phpFastCache/CacheManager.php(218): phpFastCache\Drivers\Files\Driver->__construct(Array)
#3 /opt/observium/includes/cache.inc.php(612): phpFastCache\CacheManager::getInstance('Files')
#4 /opt/observium/includes/sql-config.inc.php(310): include_once('/opt/observium/...')
#5 /opt/observium/config_to_json.php(20): req in /opt/observium/libs/phpFastCache/Core/Pool/IO/IOHelperTrait.php on line 121
ERROR: Could not load or parse observium configuration, are PATHs correct?

Fastcache disabling solve problem, but without fastcache Observium is slow.

Can you please help us.

Br,

Dmitri