code build is failed with Error while executing command: source venv/bin/activate. Reason: exit status 127

Question

I created a code pipeline with Zappa code and connected to bitbucket. I tried to build it but it is failed at codebuild step stating error.

COMMAND_EXECUTION_ERROR Message: Error while executing command: source venv/bin/activate. Reason: exit status 127

This is my buildspec.yml file

version: 0.2
phases:
  install:
    commands:
      - echo Setting up virtualenv
      - python -m venv venv
      - source venv/bin/activate
      - echo Installing requirements from file
      - pip install -r requirements.txt
  build:
    commands:
      - echo Build started on `date`
      - echo Building and running tests
      - python tests.py
  post_build:
    commands:
      - aws s3 cp backend-env s3://${S3_BUCKET} --recursive
      - echo Build completed on `date`
      - echo Starting deployment
      - zappa update dev
      - echo Deployment completed