Critical error or warning: what is the difference between them?
Short answer
Not every message from the validator means that the e-invoice is invalid or cannot be sent. The decisive factor is the severity of the validation rule that the document violated. Validators can use labels such as: Fatal , Error , Warning , Inf
Critical error
This is mainly a missing mandatory data, an incorrect XML structure, a violation of the calculation rule, an unauthorized code or a missing identifier.
Warning
Warning can alert you to a non-recommended value, missing optional data or data that may be required by a specific partner.
The meaning depends on the instrument
The labels Error, Fatal and Warning are not universally defined by law. It should be based on the documentation of the used validator.
Internal rules
It is recommended to specify which warnings are only recorded, which are corrected before sending, and who decides on the exception.
Conclusion
The difference between a critical error and a warning lies in the severity of the violated validation rule.
Act No. 222/2004 Z. z. Coll. about VAT · FAQ of the Financial Administration of the Slovak Republic from 7 July 2026 · Peppol BIS Billing 3.0
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.