Brighton and Hove Albion have been told to re-apply for permission to play at their stadium due to a technicality.
Brighton have played at the Withdean Stadium since 1999
The football club has held home games at the Withdean Stadium since 1999 while it awaits permission to build a new stadium in the city.
The local council has admitted it acted unlawfully last time it extended the club's permission to stay at Withdean, because it did not give a reason.
The club must re-submit the application to play there and install more seats.
The Seagulls are in the middle of a public inquiry into whether they can build a new 22,000-seater stadium at Falmer.
The stadium at Withdean - an athletics arena - holds about 7,000 people.
Last year Brighton and Hove City Council approved an application from the club to install 2,000 temporary seats and play there for three more years.
But after a local resident spotted the legal loophole surrounding the council's failure to give a reason for the verdict, the process must start again.
The club will be allowed to carry on holding games at the ground while the new application is dealt with, which is expected to take a few weeks.