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Troubleshoot issues

This section provides information to help you troubleshoot and resolve or work around common issues that are related to the following tasks:

  • downloading and installing the SDK

  • creating, building, or deploying canisters

  • using the dfx command-line interface

  • running the local canister execution environment

Migrating an existing project​

Currently, there is no automatic migration or backward compatibility for any projects that you might have created using previous versions of the dfx command-line interface. After upgrading to the latest version, you might see error or failure messages if you attempt to build or install a project created with a previous version of the dfx command-line interface.

In many cases, however, you can continue to work with projects from a previous release by manually changing the dfx setting in the dfx.json configuration file, then rebuilding the project to be compatible with the version of the dfx command-line interface you have currently installed.

For example, if you have a project that was created with dfx version 0.8.0, open the dfx.json file in a text editor and change the dfx setting to the latest version or remove the section entirely.

Restarting the local canister execution environment​

In some cases, starting the local canister execution environment fails due to stale state. If you encounter issues when running dfx start to start the local canister execution environment:

  1. In the terminal that displays the IC emulation the execution environment uses, press Control-C to interrupt the local canister execution environment process.

  2. Stop the local canister execution environment by running the following command:

    dfx stop

  3. Restart the local canister execution environment in a clean state by running the following command:

    dfx start --clean

    The --clean option removes checkpoints and stale state information from your project’s cache so that you can restart the local canister execution environment and web server processes in a clean state.

Keep in mind, however, that if you reset the state information by running dfx start --clean, your existing canisters are also removed.

After running dfx start --clean, recreate your canisters by running the following commands:

dfx canister create --all
dfx build
dfx canister install --all

Removing the canisters directory​

If you run into problems building or deploying canisters after successfully connecting to the IC and registering canister identifiers, you should remove the canisters directory before attempting to rebuild or redeploy the canisters.

You can remove the canisters directory for a project by running the following command in the project’s root directory:

rm -rf ./.dfx/* canisters/*

Reinstalling dfx​

Many of the bugs you might encounter can be addressed by uninstalling and reinstalling the dfx command-line interface. Here are a few ways to reinstall dfx.

If you only have one version of dfx installed in your development environment, you can usually run the following command to uninstall and reinstall the latest version of dfx:

~/.cache/dfinity/uninstall.sh && sh -ci "$(curl -sSL https://internetcomputer.org/install.sh)"

If you have modified the location of the dfx binary, you might want run the following command to uninstall the version of dfx that is in your PATH, then reinstall the latest version of dfx:

rm -rf ~/.cache/dfinity && rm $(which dfx) && sh -ci "$(curl -sSL https://internetcomputer.org/install.sh)"

Xcode prerequisite​

Some versions of the SDK prompted you to install Xcode when creating a new project on a macOS computer. The prompt has been removed and the dfx new command does not require you to install any macOS developer tools. However, you should have Developer Command Line Tools installed if you want to create a Git repository for your project.

You can check whether you have the developer tools installed by running xcode-select -p. You can install the developer tools by running xcode-select --install.

Failed build when using VMs​

If you are running dfx using a virtual machine image on Ubuntu or CentOS, you might see an error message that looks like this when you attempt to run the dfx build command:

Building hello...
An error occurred:
Io(
    Os {
        code: 2,
        kind: NotFound,
        message: "No such file or directory",
    },
)

Address in use error or orphan processes​

If you are developing projects locally, you often have the local canister execution environment running either in a separate terminal or in the background. If the local environment processes do not get properly terminated, you might see operating system errors indicating that an address is already in use or or be unable to stop processes normally using the dfx stop command.

There are several scenarios in which you might encounter this issue. For example, if you run dfx start in a local project directory then change to a different local project directory without first stopping the canister execution environment processes, you might see this issue.

If you encounter an issue where you suspect or you receive a message that an address is already in use or that a process is already running in the background, perform the following steps:

  1. Run the following command to see which process is listening to the 8000 port if you are using the default binding to localhost:

    lsof -i tcp:8000

  2. Run the following command to terminate any orphan processes:

    killall dfx replica

  3. Close the current terminal and open a new terminal window.

  4. In the new terminal, run the following command to run the local canister execution environment in a clean state:

    dfx start --clean --background

Memory leak​

Fixing memory leaks is an ongoing process. If you encounter any error messages related to memory leaks, you should do the following:

  1. Run dfx stop to stop currently running processes.

  2. Uninstall dfx to prevent further degradation.

  3. Re-install dfx

  4. Run dfx start to restart replica processes.

Alternatively, you can remove the .cache/dfinity directory and re-install the latest dfx binary. For example:

rm -rf ~/.cache/dfinity && sh -ci "$(curl -sSL https://internetcomputer.org/install.sh)"