If any municipality in this state, including those operating under a special charter, having the power to construct or cause to be made improvements consisting of grading, paving, graveling or any other form of improvement to its streets, avenues, alleys, sidewalks, gutters, sewerage or drainage, has levied or assessed or charged the cost thereof against the property abutting thereon and to the owners thereof, and has paid such cost and has not been paid therefor in full, and if in the judgment of the governing authorities of said municipalities, errors or irregularities have occurred in the assessing or computing of such cost, then such municipality is hereby authorized and empowered to ascertain the cost thereof and to add thereto accrued and unpaid interest, and to declare the same by resolution, and to correct errors or irregularities in said former assessment or assessments accordingly. In no event, however, shall the principal amount thereof, exclusive of interest, be increased.

When such errors or irregularities have been corrected, the assessment or assessments so made, and all steps and proceedings leading up thereto or precedent thereto are hereby confirmed and validated for all purposes and against all persons, and said assessment or assessments shall be in lieu of the assessment or assessments in which said errors or irregularities have been made or occurred. Such further proceedings may be had thereon to provide for and fix a lien on said property to secure the payment of said assessment or assessments, and for enforcing the collection thereof, and otherwise, in the same manner as is provided in this chapter, when valid assessments have been made that are not erroneous or irregular.

All orders, resolutions, ordinances, and proceedings relative to sidewalk, curb, or gutter improvements heretofore passed and adopted by any such municipality or its governing authorities, are hereby in all things made valid and binding regardless of defects or omissions or informalities or the failure to comply with any law or part of law relative thereto.

If and when it shall have been determined by said governing authorities that an over-assessment shall have been made against such person or property, such governing authorities are hereby authorized and empowered to give credit for or refund the amount of such excess.