24-year-old Bopp only arrived on a free transfer from Rotherham Unuted and signed a 3-year deal with the Railwaymen.
Since his arrival Bopp has been blighted with fitness and injury and has only made three starts and a further three appearances as sub netting only once in the game against Hudderfield Town back in September.
The Kiev born midfielder has only just recovered from a foot injury but has found himself down the pecking order with the likes of Gary Roberts, Michael O'Connor, Mark Carrington and Steven Schumacher all ahead of the player.
Holland told the official website "Eugen is still here but he has been made available for transfer. At this stage I am not aware of any interest but he would be available on a free transfer, having joined us on a free transfer in the summer.
"He is a terrific lad and his attitude and application has been very good to the training. He is a very professional player, but it hasn't quite worked out for him.
"In the summer we looked at it and thought that if we could bring in a player on a free transfer that could be better than what we have then we should do. We felt that with Boppy and he wanted to come here