Shaun Edwards will not be taking up a role with Toulon after the Welsh Rugby Union (WRU) reversed its decision to allow the Wales defence coach to double up on his duties.
The former rugby league great had been expected to begin working with the Top 14 club next week after the WRU had initially agreed to the move.
However, the governing body back-tracked on that call this week.
"Shaun will not be working with Toulon," said a WRU statement.
"He is a contracted employee of the WRU.
"Whilst we encourage coaching staff gaining experience in other environments, the scope of the opportunity has changed and would represent an unacceptable compromise.
"Shaun remains committed to Wales up to RWC 2019."
Edwards' stock has risen during his time in the Wales coaching set-up under Warren Gatland after playing his part in three Six Nations triumphs - including two Grand Slams - and a run to the World Cup semi-finals in 2011.