Four Cardiff City fans arrested at Reading in January's FA Cup tie have been released with no further action, Thames Valley Police have confirmed.
The force initially said the four were arrested for "alleged racially aggravated abuse".
Cardiff, who dispute the allegations, subsequently demanded an apology.
"All four people who were arrested in connection with this incident have been released with no further action," said Thames Valley Police.
"The investigation has been filed."
After the incident during the 2-2 draw in January, Reading said they would review their match-day protocols.
They also offered an apology to the majority of Cardiff fans who attended the match - but they stood by a decision to report Bluebirds fans for "discriminatory chanting".
Tensions between the clubs resurfaced later in January when they drew 1-1 in the Championship at Cardiff City Stadium.
A fan was ejected from the Reading end of the ground after Cardiff supporters complained he made an allegedly offensive gesture during the first half.