The council has previously said any sale would depend on DePree having "a commercially viable business model to secure the long term future of the hall".
Last November, the council said it had decided not to renew the option agreement after consultants said his plans were "unlikely to be able to secure future public or private funding".
At that time, a council spokesman said DePree "had not been able to produce a viable proposal, which it said was a condition of the sale, despite having had seven years to do so". The authority said it "had a responsibility to explore alternative options" in order to "protect the public monies invested to date".
In November, council leader Neil Emmott said: "Mr DePree was asked to meet a number of conditions when we entered into our agreement with him. We would be failing in our duty to protect our historic assets if we didn't hold Mr DePree to the terms of this agreement."
The council said it spent £557,000 between 2017 and 2024 for essential repairs, with almost £1m contributed by Historic England. The council said it was now spending a further £700,000 on roof repairs and a feasibility study.
According to DePree's legal documents, the council has also argued that the planning permission was insufficient to meet the terms for a sale under the agreement. He is disputing that.
He is also disputing whether he needed to provide a viable business model to comply with the conditions for a sale, and his court papers say he does have "a clear vision, a plan and the resources to rescue Hopwood Hall".