Unable to Import Lambda Function Module: No module named 'lambda_function'

Question

I'm encountering an issue with deploying a Python-based AWS Lambda function. Despite following various troubleshooting steps, I'm consistently getting the error message "Unable to import module 'lambda_function': No module named 'lambda_function'" when testing the Lambda function in the AWS Lambda console.

"lambda_function.py" is located in the same directory (lambda_package) in the ZIP file (lambda_package.zip), along with the required packages like below. 
```
lambda_package/
├── lambda_function.py
├── pyotp
│   ├── ...
├── pyotp-2.9.0.dist-info
│   ├── ...
├── python_dotenv-1.0.1.dist-info
│   ├── ...
├── requests
│   ├── ...
├── requests-2.31.0.dist-info
│   ├── ...
```

In my AWS SAM template, the handler configuration for the Lambda function is specified as lambda_function.lambda_handler.

The lambda_function.py script looks like this: 
```
import pyotp
import os

def lambda_handler(event, context):
    # Code here
```

Despite ensuring that the file name, ZIP structure, and handler configuration are correct, I'm still encountering this import error. I've tried redeploying the function multiple times but getting the same  error like this:
"[ERROR] Runtime.ImportModuleError: Unable to import module 'lambda_function': No module named 'lambda_function'
Traceback (most recent call last):"

Any insights or suggestions would be greatly appreciated.

Mina Gobrial - OptimeCloud · Accepted Answer

The structure you provided seems correct, but it's worth double-checking that lambda_function.py is indeed at the root of the ZIP archive and not inside another folder. The structure inside the ZIP should not have lambda_package as a top-level directory. If you open the ZIP file, you should immediately see lambda_function.py and the directories for your dependencies, like so:

```bash
lambda_function.py
pyotp/
pyotp-2.9.0.dist-info/
python_dotenv-1.0.1.dist-info/
requests/
requests-2.31.0.dist-info/
```

Use the following command from the directory containing lambda_function.py and the dependency directories:

```bash
zip -r9 ../lambda_package.zip .
```
If this has answered your question or was helpful, accepting the answer would be greatly appreciated. Thank you!

Unable to Import Lambda Function Module: No module named 'lambda_function'

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