Block gas limit lower than required to deploy a contract

Question

I am trying to deploy a contract on ropsten network that requires ~7000000 gas, however the current gas limits are ~3.5mil on ropsten and I am unable to deploy the contract. What can I do about this?

Answer 1

Could you share your contract code so we can try to see what's causing the high deployment cost?

There may or may not be an easy solution to this problem. You should check how much gas is being spent on the size of your compiled contract code, and how much is being spent on executing the contructor function.

Try to reduce the size of your contract by:

• Compiling it with optimization enabled

• Manually optimizing your code for size. Remove duplicate code, and remove code that is not strictly necessary. If some function is only needed client-side, remove it from the contract and implement it client-side.

• Splitting functionality into multiple contracts

Try to reduce the gas cost of your constructor function by:

• Reducing the size and amount of constants (e.g. array literals, string literals)

• Reducing the amount of writes to storage. Every storage slot of 256 bits costs 20000 gas, so setting a uint256 costs 20000, setting a 64 character string costs 60000.

• Limit the amount of calls to functions in other contracts

• If there are loops in your constructor function, try to limit the amount of iterations

• Generally limit the amount of work performed in the constructor function

Answer 2

Use a different testnet! At the time of this writing, the latest blocks in each testnet had a block gas limit of:

1. Rinkeby: 10 million (see block)
2. Kovan: 12.5 million (see block)
3. Goerli: 30 million (see block)

Otherwise you can also always try and reduce the contract size, see here.