Parameter file not is not working in Code Build template

I have created a codebuild solution. It is able to create stack when the parameters are assigned in the template.yml file. But when the parameters are defined into a separate file, unable to create the Changeset. I have added TEMPLATE_PATH = template.yml and PARAM_FILE_NAME = param.json in codebuild environment variable. template.yml look like ---->

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: CloudFormation template to create lambda layer
Parameters:
  pPyPackageBucket:
    Type: String
    Description: S3 Bucket for software lib package
Resources:
  LambdaLayer:
    Type: 'AWS::Lambda::LayerVersion'
    Properties:
      CompatibleRuntimes:
        - 'python3.9'
      Content:
        S3Bucket: !Ref pPyPackageBucket
        S3Key: 'package/python.zip'
      Description:  'Python package'
      LayerName:  'pandas'

param.json look like ---->

{
    "Parameters": {
        "pPyPackageBucket": "s3-my-softwares"
    },
    "StackPolicy": {}
}

buildspec.yml look like ---->

version: 0.2
phases:
  pre_build:
    commands:
      - . ${CODEBUILD_SRC_DIR}/build-scripts/pre_build.sh
  build:
    commands:
      - . ${CODEBUILD_SRC_DIR}/build-scripts/build.sh
artifacts:
  files:
    - ${TEMPLATE_PATH}
    - ${PARAM_FILE_NAME}
  discard-paths: no

Getting the below codebuild error:

Failed to create changeset for the stack: cicd_lambda_layer, An error occurred (ValidationError) when calling the CreateChangeSet operation: Parameters: [pPyPackageBucket] must have values.

How to resolve this issue?