EHPDFHeadlessDocumentError

This exception in HPDFHeadlessDocument exposes a read-only Code property of type THPDFHeadlessDiagnosticCode together with a human-readable Message

The constructor accepts a diagnostic code and a detail string; document callers should branch on the code rather than parsing message text

Operating-system I/O and codec failures may keep their native exception types; cancellation uses EHPDFOperationCancelled