How can we implement software when the customer's business model is not fixed?

I don't know who has encountered this problem.

Originally, the problem was very simple. Party A wants to build an automobile club, an e-commerce website, outsourcing of project implementation, and Party B (a software company) as the contractor. As a result, the construction period will be delayed. The contract stipulates that the project will be completed on April 1, May 1, and the project will not be completed on April 1, June 10.

Background: Party A's business is a new business. The company has just been established for three months and its business model is not fixed. For example, Party A does not know when its business process will change or what it will look like (some may say that it can be used as a process engine. Haha, Party B thinks that the construction period is too short and there is too little money ). Party B is confused about the list.

In this case, prepare the implementation software. This is troublesome. During Party B's development, Party A constantly overwrites its own needs. Party B was very depressed.

Root cause: the contract is extremely informal and Party A's requirements are rough. For example, there is a piece of "provide the corresponding Forum. After Party A submits the request, it does not receive anyDetailed Solution.

Alas! It is a delayed project. I don't know how many projects in China will be completed on time according to the contract. This time I changed my role and I also became an invigilator.