West Ham have been fined £30,000 by the Football Association after admitting to a whereabouts breach of anti-doping regulations.
The Hammers accepted a charge after three whereabouts violations in one year, saying the errors were administrative in nature.
There must be a daily time window when players are available for testing by anti-doping control officers.
A statement from the FA read: "West Ham United have been fined £30,000 after admitting a charge of failing to ensure that their club whereabouts information was accurate three times within 12 months, contrary to The FA's anti-doping regulations."
A West Ham United spokesperson said: "The club accepts the charge and we will endeavour to tighten our procedures to avoid this happening again.
"The breach related to administrative oversights on The FA's whereabouts system, where for example a player's address had been registered and the house number digits transposed.
"We would like to reiterate that the breach was a club administrative matter and did not concern any of our players."