Error code 5 reflects a non-descript exit condition and is harmless.
In versions of HAAst prior to 2017 a warning with exit code 2 (in the case of MySQL database/table synchronization) means that differences were found between the source and destination tables but they were successfully synchronized. Other exit codes in this context are 0 (success, no differences), 1 (error condition), and 3 (combination of 1 and 2)
In version of HAAst from Jan 2017 onwards exit code 0 always means success (even if differences were found and then synced successfully).
No action is required; this is a normal exit code and indicates synchronization is working. We have notified the author of the library we use in the hope of a more appropriate exit code.
