phpfastcache: Randomly getting the phpFastCacheIOException

Configuration

• PhpFastCache version: 6.0.2
• PhpFastCache API version: 1.2.5
• PHP version: PHP 7.0.30-0ubuntu0.16.04.1 (cli) ( NTS )
• Operating system: Ubuntu 16.04

I am using this since more than a year, and getting such permission exception once in a month or so. It is completely random behavior and has no specific steps to duplicate it. Can anyone help with that?

I have checked the CacheManager class and the default setting is 'default_chmod' => 0777,

here are my doubts

1. Should I use the "autoTmpFallback" = true in settings?
2. If this is write permission issue, then it should trigger exception on every try of writing content to directory. so can anyone help me find the exact issue?

here is the detailed log of the exception message.

Fatal error: Uncaught phpFastCache\Exceptions\phpFastCacheIOException: PLEASE CHMOD /tmp/beta/Auto/Files/73/74 - 511 OR ANY WRITABLE PERMISSION! in /var/www/html/beta/web_services/vendor/phpfastcache/phpfastcache/src/phpFastCache/Core/Pool/IO/IOHelperTrait.php:157

Stack trace: #0 /var/www/html/beta/web_services/vendor/phpfastcache/phpfastcache/src/phpFastCache/Drivers/Files/Driver.php(72): phpFastCache\Drivers\Files\Driver->getFilePath('all_types')

#1 var/www/html/beta/web_services/vendor/phpfastcache/phpfastcache/src/phpFastCache/Core/Pool/CacheItemPoolTrait.php(353): phpFastCache\Drivers\Files\Driver->driverWrite(Object(phpFastCache\Drivers\Files\Item))

#2 /var/www/html/beta/web_services/vendor/phpfastcache/phpfastcache/src/phpFastCache/Helper/Psr16Adapter.php(84): phpFastCache\Drivers\Files\Driver->save(Object(phpFastCache\Drivers\Files\Item))

#3 /var/www/html/beta/web_services/_HELPER.php(1257): phpFastCache\Helper\Psr16Adapter->set('all_types', Array, 1200)

#4 /var/www/html/beta/web_services/service.php(417): HELPER in /var/www/html/beta/web_services/vendor/phpfastcache/phpfastcache/src/phpFastCache/Core/Pool/IO/IOHelperTrait.php on line 157