Struggling to deploy on Heroku? Here`s how to fix the common `command not found` error with code snippets

Table of content

  1. Introduction
  2. Understanding the 'command not found' error on Heroku
  3. Checking your package.json file for errors
  4. Adding the scripts to your package.json file
  5. Updating your Heroku buildpacks
  6. Fixing the error with code snippets
  7. Conclusion


If you're new to deploying on Heroku, chances are you've encountered the dreaded "command not found" error at least once. Don't panic! It's a common error that can be fixed with a few simple steps. In this guide, we'll cover the causes of this error and provide some helpful code snippets to help you get past it.

Deploying on Heroku can be intimidating, especially if you're not familiar with the platform. But once you get the hang of it, it's actually quite easy. The key is to take it one step at a time and not get overwhelmed by the details. With a little patience and persistence, you'll be deploying your app on Heroku in no time.

So, if you're struggling with the "command not found" error, don't give up! Just keep reading and we'll guide you through the process of fixing it. We'll be using Python as an example, but the same principles apply to other languages as well. So whether you're a seasoned developer or a beginner, this guide is for you!

Understanding the ‘command not found’ error on Heroku

If you've ever encountered the 'command not found' error on Heroku while trying to deploy your app, you know how frustrating it can be. But don't worry – this error is easily fixed with a few simple code snippets. The first step is to understand what's causing the error.

The 'command not found' error occurs when Heroku can't find the command you're trying to run. This can happen for a few reasons. One common cause is a missing dependency – if your app relies on a package or library that isn't installed, Heroku won't be able to run the necessary command.

Another possible cause is a problem with your environment variables. Heroku uses environment variables to store sensitive information like API keys and database credentials, and if these variables aren't set up correctly, you may encounter the 'command not found' error.

To fix this error, you'll need to diagnose the specific cause and then implement the appropriate solution. This might involve installing missing dependencies, double-checking your environment variable settings, or using a different buildpack.

By understanding the 'command not found' error and knowing how to fix it, you'll be well on your way to successfully deploying your app on Heroku.

Checking your package.json file for errors

One common reason for the 'command not found' error on Heroku is an error in the package.json file. This can often occur because of a missing or misspelled dependency or script. To avoid this error, it is important to check your package.json file before deploying your code to Heroku.

To start, make sure all the necessary dependencies are listed in the "dependencies" section of the file. If you're not sure which dependencies are required, you can use the "npm install" command, followed by the name of the package you want to install. This will also update your package.json file automatically, adding the latest version of the package you just installed.

Next, check your "scripts" section for any typos or syntax errors. Make sure all scripts are spelled correctly and that the syntax is correct for running the command or script. You can also use the "npm run" command, followed by the name of the script, to test it out and see if it runs correctly.

If you have multiple scripts in your package.json file, such as a "start" script and a "build" script, make sure they are listed in the correct order. The "start" script should come first, followed by any other scripts you want to run.

By taking the time to check your package.json file, you can avoid the common 'command not found' error on Heroku, and deploy your code successfully.

Adding the scripts to your package.json file

If you're running into the "command not found" error when trying to deploy your app on Heroku, it could be because your package.json file is missing necessary scripts. Here's how to add them:

  1. Open your package.json file in your text editor.
  2. Under the "scripts" section, add the following:
"scripts": {
  "start": "node index.js",
  "test": "echo \"Error: no test specified\" && exit 1"
  1. Replace "node index.js" with the command used to start your app locally (e.g. "python" for a Python app).
  2. Save the changes and try redeploying your app on Heroku.

By adding these scripts, you're telling Heroku how to start and test your app. This should resolve any "command not found" errors you were encountering before.

If you're still having trouble deploying your app, don't hesitate to refer to Heroku's documentation or reach out to their support team for assistance. They're there to help you get your app up and running smoothly.

Updating your Heroku buildpacks

If you're encountering the 'command not found' error when deploying your Python app to Heroku, you may need to update your Heroku buildpacks. Here's how to do it:

  1. Open your command line interface and navigate to your Heroku app directory.
  2. Type "heroku buildpacks" and hit enter. This will display the currently installed buildpacks for your app.
  3. If the Python buildpack is not listed, you need to add it. Type "heroku buildpacks:add heroku/python" and hit enter.
  4. If the buildpack is already listed but not working correctly, you may need to update it. Type "heroku buildpacks:clear" and hit enter. Then, type "heroku buildpacks:add heroku/python" and hit enter to reinstall the buildpack.

Once you've updated your buildpacks, try redeploying your app to see if the 'command not found' error has been resolved. If you're still experiencing issues, double-check that all necessary dependencies and requirements are properly listed in your project files and try again.

Fixing the error with code snippets

When it comes to deploying your Python application on Heroku, you may encounter the common 'command not found' error. Don't worry, it's a common issue that can be easily addressed with a few code snippets.

First, check if the required packages are installed by running the following command in your terminal:

pip freeze

This will display a list of all the installed packages, and you can check if the required packages are present in the list.

If the required packages are missing, you can install them using the following command:

pip install -r requirements.txt

Make sure you have a requirements.txt file in your project that contains a list of all the required packages with their versions.

If the error persists, try specifying the path to the required command directly in the Procfile. For example, if the error is for the 'gunicorn' command, you can update the Procfile as follows:

web: /app/.heroku/python/bin/gunicorn app:app --log-file=-

This will ensure that Heroku can find the 'gunicorn' command in the correct path and run your application without any errors.

These are some common ways to fix the 'command not found' error when deploying your Python application on Heroku. Keep experimenting and learning through trial and error, and you'll soon become an expert in deploying Python applications on Heroku without any issues.


In , deploying on Heroku can be a daunting task, but with the right knowledge and tools, it can be a smooth process. One common issue that may arise is the 'command not found' error, which can be frustrating. However, by ensuring that all necessary dependencies and add-ons are installed, as well as using the correct command syntax, this error can be fixed.

It is important to remember that learning Python, or any programming language, takes time and patience. Starting with the official tutorial and practicing regularly are key steps to gaining proficiency. It is also important to seek out additional resources, such as online forums, blogs, and social media groups, for both advice and inspiration.

On the other hand, it is crucial to avoid common mistakes like purchasing complex books or using advanced IDEs before mastering the basics. Learning through trial and error is often the best approach, as it allows for experimentation and a deeper understanding of the language.

In summary, deploying on Heroku and learning Python can be challenging, but it is also rewarding. By following the steps and advice outlined in this article, you can overcome common errors and gain confidence in your abilities. Remember to stay patient, persevere through challenges, and seek out resources to aid your learning journey.

My passion for coding started with my very first program in Java. The feeling of manipulating code to produce a desired output ignited a deep love for using software to solve practical problems. For me, software engineering is like solving a puzzle, and I am fully engaged in the process. As a Senior Software Engineer at PayPal, I am dedicated to soaking up as much knowledge and experience as possible in order to perfect my craft. I am constantly seeking to improve my skills and to stay up-to-date with the latest trends and technologies in the field. I have experience working with a diverse range of programming languages, including Ruby on Rails, Java, Python, Spark, Scala, Javascript, and Typescript. Despite my broad experience, I know there is always more to learn, more problems to solve, and more to build. I am eagerly looking forward to the next challenge and am committed to using my skills to create impactful solutions.

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