Logs show the following errors:
Dec 21 11:55:11 example-server kernel: EXT4-fs (sda2): error count since last fsck: 7
Dec 21 11:55:11 example-server kernel: EXT4-fs (sda2): initial error at time 1524389586: ext4_journal_check_start:56
Dec 21 11:55:11 example-server kernel: EXT4-fs (sda2): last error at time 1524391685: ext4_journal_check_start:56
Step 1 - Insert installation media as an .iso into the virtual machine (VM) or as physical media in the form of a disc or USB device into the Syslog-ng Store Box (SSB) appliance. (note - the installation media must match the version of the VM or SSB appliance currently being run)
Step 2 - Reboot the VM or SSB appliance ensuring that upon boot the installation media is used as the primary boot device.
Step 3 - Select "Recovery shell" from the installer menu
Step 4 - Run fsck from within the "Recovery shell" using the following command:
Step 5 - Once done, reboot the VM or SSB appliance without the installation media. The errors should cease.