What is Islam's ruling on the annual maintenance contract for a specified sum of money, knowing that the sum is paid whether a malfunction occurs or not?

This contract is invalid because it contains gharar (excessive uncertainty), which is forbidden in Islamic law. Gharar refers to a transaction whose outcome is unknown or involves risk, because leasing is similar to selling in this regard. If a defect occurs, the amount taken may be without an مقابل (equivalent value), or its repair may cost more than the amount paid.