The customer get the following error when trying to retrieve a context attribute :
[EXE - 16064]: Context attribute read  error

Generally, here is the sequence used :

Create the attribute : setContextAttribute("Identifier", "xxx")
Retrieve the attribute : getContextAttribute("Identifier")
Remove the attribute : removeContextAttribute("Identifier")

There are several possible causes of such error :
1. The parameter provided to the getContextAttribute is not consistent with the setContextAttribute
setContextAttribute("Identifier", "xxx")
setContextAttribute("Identifier2")
2. the configuration is correct, but :
- the customer is using several processing engines
- the ContextAttribute are not unique
-> it can happen that a processing engine removes a ContextAttribute and that another processing engine is trying to get the same ContextAttribute that does not exist anymore