Which means the invoice didn't pass validation?
Short answer
This means that the system has found an error on the invoice and the invoice does not yet meet all the requirements for an electronic invoice. This does not automatically mean that the invoice is accountingly incorrect or contains incorrect prices. This means only that some data need to be corrected before dispatch or processing. Some errors are technical, others are related to the content of the invoice.
Blocking error
The document should not be sent or exported as ready.
Warning
It does not always need to block, but may entail operational or accounting risk.
Technical correction
Some errors can be repaired safely without altering accounting truth.
A Man Decides
For the content of the invoice, dates, VAT and the parties must not decide AI alone.
Conclusion
Not legal advice. Machine-translated answer, not yet manually reviewed. For the exact wording, see the Slovak original.