Source File requires different compiler version

Question

I am using solidity version "pragma solidity ^0.4.20;". When I checked JSON files of contract, compiler version shows :

"compiler": {
    "name": "solc",
    "version": "0.4.21+commit.dfe3193c.Emscripten.clang"
  }

Still I am getting error :

Source file requires different compiler version (current compiler is 0.5.0+commit.1d4f565a.Emscripten.clang - note that nightly builds are considered to be strictly less than the released version

Command 'truffle version' gives :

 Truffle v4.1.5 (core: 4.1.5)
 Solidity v0.4.21 (solc-js)

Answer 1

During solidity (solc) 0.5 releases the different frameworks like solc, truffle, web3, openzeppelin had a timeframe where some had a 0.5 compatible version released and some didn't. I think you could have changed specified the solc version like here (didn't try that) but meanwhile all of the mentioned fully support 0.5 (openzeppelin since 2 days ago at time of writing).

Consider doing the following

npm outdated
npm install [my-outdated-package] #repeat for all outdated packages
rm -R -f build #cleanup step (might not be necessary)
rm -R -f node_modules #cleanup step (might not be necessary)
npm install
truffle compile #(will still fail)

Check with truffle version in a terminal window at some other place (not project dir) if it matches the current release here otherwise do this:

npm uninstall -g truffle
npm install truffle

Usually you should avoid installing global packages but e.g. BlockCatIO/solidity-flattener requires that solc is installed globally because of certain features (installation described here). Remember to upgrade that one too.

When you then run truffle-compile you should still see errors because they changed the syntax of pragma (found that here).

So change:

#old
pragma solidity ^0.4.20;

#new
pragma solidity >=0.4.20;

I also recommend upgrading ganache-cli (I had problems running the tests with old version):

npm install -g ganache-cli

You might then still see compile errors but that's what makes v0.5 great because they made some improvements you should troubleshoot one-by-one

Here the Breaking Changes in Solidity 0.5.0

Doing this I got it compiling again :)

Answer 2

Thanks, I was using visualstudio editor and enabled an extension for solidity where compiler version was upgraded. By specifying the version of compiler in Editor resolved the issue for me.

Answer 3

I would recommend using solc-select (https://github.com/crytic/solc-select), it will allow switching easily between solc versions.

Answer 4

I had the same issue and by doing following, my error disappeared.

The syntax change in pragma is giving error. just Change pragma solidity ^0.4.20; to pragma solidity >=0.4.20;.

Answer 5

What worked for me is the following:

1. Type ctrl+SHIFT+p
2. Select solidity:Change Global compiler version (Remote)
3. Select your desired solidity version
4. Additionally, I needed to change in the setting of solidity extension by Juan Blanco. Click on the settings icon and go to extension settings
5. Set Solidity default compiler option to remote

Answer 6

Try format of compiler at first line of Contract .sol :- pragma solidity >=0.4.21 <0.6.0

It worked for me. Hope this helps,

Answer 7

I had the same issue and by doing following, my error disappeared.

The syntax change in pragma is giving error. just Change pragma solidity >=0.7.0 <0.9.0;.

Post doing this you will get an warning

Warning: SPDX license identifier not provided in source file. Before publishing, consider adding a comment containing "SPDX-License-Identifier: " to each source file. Use "SPDX-License-Identifier: UNLICENSED" for non-open-source code. Please see https://spdx.org for more information.

Just add it above pragma line.

// SPDX-License-Identifier: GPL-3.0

Answer 8

Fix

Change the source of the compiler for the extension:

• Open the command palette ctrl+p
• Type > followed by Change the default workspace
• Select remote and then Change Global compiler version (Remote) to your version, or an option that suits your project the best.
• You can read more about it here
• Keep the grind

Reference

https://cesarvarela.com/blog/fix-source-file-requires-different-compiler-version.

Answer 9

So this is how you solve this compiler version problem.(Worked for me)

Right click the pragma solidity statement, and select the following option:

Solidity: Change workspace compiler version (Remote)

Then, all you have to do is select the Solidity compiler you want.

Answer 10

Run npm install solc go to package.json check the version of solc after go to truffle.config.json replace he version make sure its the same as in package.json change it on sol ils too

Answer 11

I ran into a similar error and I updated my file with the following

//SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.7.0 <0.9.0;

Consider making these changes and your project will update

Answer 12

Go to Settings of VS Code. Choose default compiler => remote

choose and copy paste the version you want to support https://etherscan.io/solcversions

Answer 13

If you're using Juan Blanco's Solidity extension for VS Code, besides the compiler version in the truffle-config.js you will also have to change the compiler version of the extension itself. To do that:

1. Open VS Code command palette by pressing Ctrl+Shift+P
2. Type Solidity: Change global compiler version (Remote) then press enter
3. This will open another menu from which you can select the desired version

NOTE: Only changing the extension's compiler version will actually allow you to compile your contract causing some warning. Nevertheless, it is important to also change the compiler version in the truffle-config.js file, because when compiling outside of your VS Code instance, the version specified that file will be used. You can verify that by running truffle compile --compiler in the terminal.

Answer 14

Just add this :

    compilers: {
solc: {
  version: "^0.4.20"
}
}

Where "^0.4.20" is the version of the compiler you want to use.

So your truffle config file should look like this :

   module.exports = {
     networks: {
       development: {
         host: "127.0.0.1",
         port: 7545,
         network_id: "*" // Match any network id
       }
   },
    compilers: {
      solc: {
        version: "^0.4.20"
         }
       }
     };

And the problem will be solved :)

Don't forget to check the documentation : https://trufflesuite.com/docs/truffle/reference/configuration/#compiler-configuration