Symptoms
Attempt to make a purchase from CCP2 fails - nothing happens on clicking "Finish" button of the sales wizard. Console log of the browser shows exception:
Returned status 500. Message: Communication Failure: Server 'billing_XXXX' is not available.
In the /var/log/pa/billing.log it can be seen that CalcSalesOrder_API causes a restart as EZTAX.CalculateTaxes does not return any result:
[XX-XX-XX XX:XX:XX.XXX ContainerAu RQ00000 THXXXXX TRC] Remote container billing_XXXXX <XX:0:0> stopped.
...
[XX-XX-XX XX:XX:XX.XXX ContainerAu RQ00000 THXXXXX TRC] Remote container billing_XXXXX <XX:0:0> started.
Cause
The issue is caused by the bug with id #PBA-80978 ("Error 500 in CCPv2 if EZTax not configured").
Resolution
Reconfigure taxation - either setup EZTax or configure correct taxes which are to be calculated by BA.