Automatically reject questionnaires with errors

Automatically reject questionnaires with errors upon syncing from the interviewer’s tablet.

What do you mean by ‘automatically’? ANY and ALL incoming interviews should be rejected? I’m sure you don’t want that. Most likely, you are thinking of having some kind of logic that validates data and rejects those interviews which do not satisfy the requirements.

There is no in-built functionality in Survey Solutions that you’d define such a logic and actions (of course, other than in-questionnaire validations that display errors/notifications on the tablet to the fieldworkers). So to implement such a workflow you would:
a) export all/new data
b) run the logic in the appropriate environment (R, Excel, Stata, Python, etc etc)
c) reject interviews

This can be done manually (I would not ignore this option) quite effectively - a person responsible does daily export, runs the validation scripts and rejects what needs to be rejected. Or, if there are appropriate skills, time to develop and test, and once again the skills, all this can be further automated by using API calls to chain a) and c) steps to the running script.