Gareth Barry's impending return to West Bromwich Albion has suffered a setback over a clause in his previous contract with former club Everton.
The ex-England midfielder, 38, was a free agent when he was released by Albion in June after his contract at The Hawthorns expired.
Albion then said that they might like to offer him a new deal after all - but Everton would be due a further payment.
"It's frustrating for us and for him," head coach Slaven Bilic told BBC WM.
"We had a meeting yesterday. The deal is agreed with him but we have that situation with Everton.
"There is a little clause. I spoke to the board and we are doing everything we can.
"He would be a major boost for us and one that comes from within too. He already knows the place and most of the players.
"We have a lot of young players. At times they need the kind of support that he can bring."
Barry was signed for Albion by then Baggies boss Tony Pulis from Everton in July 2017.
After making 55 first-team appearances, plus one for Albion's under-21s, news of Barry's release was issued at the end of last season when the Baggies were still managerless following their failed attempt to win promotion from the Championship.
But Bilic was keen to bring him back - and he remained involved over the summer while he recuperated from a knee operation.
The former Brighton junior, who won 53 England caps while with Aston Villa and Manchester City, played 653 times in the Premier League - more than anyone else since the top flight was rebranded in 1992.