Word to describe a computer system that is more error accepting?
"Robust" is sometimes used to convey the system behavior you describe, with the positive connotation.
For example:
Despite what user input comes its way, the program does not crash. It is very robust.
flexible, tolerant. But you may be better off using two words or a compound word. I'd use fault-tolerant.
For example:
Even though the user formatted the date incorrectly, it handled the mistake gracefully. It is fault-tolerant.
This is a resilient system.
This is a good word to talk about fault-tolerant system.