Consequences of early exit from a warehouse tenancy contract

Greetings,

Dear Sir,

I have rented one warehouse in Feb 2018 and want to terminate my contract because of financial issues, but the landlord is demanding 4 months rent as a penalty.

Please be noted that in the contract, the termination clause is mentioned as "Termination of the tenancy contract is possible only after fully agreed terms by both parties".

Kindly advise, and also give any reference form law section.