§ 866.Error, Irregularity, Omission Not Affecting Substantial Rights Disregarded

Validation proceedings deal with technical, often complex public financing and contracting matters, where minor procedural slips are common. Section 866 tells the court not to let that kind of harmless imperfection derail the case: any error, irregularity, or omission that doesn't affect the substantial rights of the parties gets disregarded.

This is a substance-over-form instruction. A validation action is meant to answer the real question -- is the matter valid -- rather than get sidetracked by defects that don't harm anyone's rights.