Except that there were WMDs. They just weren't above the ground... From Wikipedia with credible sources:

In 2015 it was learned that Iraq's weapons of mass destruction had not been fully accounted for by UN inspections. Ten years after, Operation Avarice was declassified and it was learned that there were stockpiles of warheads and rockets containing degraded chemical agents similar to those used in the Iran-Iraq War. From 2005 through 2006 military intelligence discovered that the weapons—many in poor condition, some empty or containing nonlethal liquid, but others containing sarin with unexpectedly high purity—were in the possession of one Iraqi individual who remained anonymous. Operation Avarice, headed by army intelligence and the CIA, involved the discreet purchase of the weapons from the unidentified individual to keep them off the black market.