Cook County Deputy Chief Information Officer Derrick Thomas [left] and Tyler Technologies executive Mark Hawkins speak during a meeting on Wednesday.

A long-delayed software upgrade designed to liberate Cook County’s tax offices from a decades-old computer mainframe will be delayed by at least another nine months, county technology officials told disgruntled commissioners on Wednesday. And in the meantime, officials suggested the tumultuous switch could put the county’s tax bills in jeopardy.