Which Agreement Does Not Have Legal Existence? Types of Non-binding Agreements and Contracts

A void agreement has no legal effect. An agreement without necessary elements is void. Void contract does not create obligation.
An agreement not enforceable by law is not a contract. Illegality must result from performing the contract itself.
Agreements to exist in future are void unless all terms are agreed.
An arbitration clause in an agreement is enforceable pending payment of stamp duty on the main contract.
To terminate a contract, negotiate ending it. You may have to pay a fee. Duress is a defense against enforcing a contract or damages.

Contracts require contractual capacity and consideration. Commercial agreements intend legal relations unlike social agreements. Promise to buy goods is enforceable if other requirements exist.

An illegal agreement under common law is unenforceable. If agreement becomes illegal after making, it becomes unenforceable. Previous payments must be returned.
If a contract becomes illegal, it becomes unenforceable.
The law does not recognize illegal or immoral contracts.