The Austrian centre-half, 31, has returned to the continent to be closer to his young family after a memorable spell at Oakwell following his arrival in January, 2020.
Sollbauer, who had a year left on his deal, was widely viewed as a catalyst for the Reds’ ‘Great Escape’ in the second half of the 2019-20 campaign after being brought in by ex-head coach Gerhard Struber from Wolfsberger AC and made a strong contribution to the club reaching the play-offs last term.
Covid restrictions ensured that Sollbauer has spent all of his time in England away from his family, who did not see the Reds player in action at his place of work and had to follow his fortunes via the internet and television.
Commenting on Sollbauer’s departure, Conway said: “The board of directors at Barnsley Football Club would like to thank Michael for his incredible service to the club for the last two seasons.
“Michael provided incredible commitment to the club and set a great example of professionalism for the entire squad.
“When Michael asked to be able to return to Europe to reunite with his family, we absolutely had to reciprocate his professionalism and allow this move.
“We will all be following Sole in his new journey and wish him and his family the best.”
Leeds United’s PolishUnder-21 international midfielder Mateusz Bogusz has returned to Spain for a second loan spell after joining Spanish Segunda Division side UD Ibiza for the 2021-22 season.
Bogusz spent last term on loan at a club at the same level in UD Logrones.