CodeDeploy Pipeline Failures from appspec Missing Files

Here's my appspec.yml file:

version: 0.0
os: linux
files:
  - source: /
    destination: /home/ec2-user/myapp
hooks:
  BeforeInstall:
    - location: scripts/remove_root_dir.sh
      timeout: 900
      runas: root
  ApplicationStart:
    - location: scripts/install_dependencies.sh
      timeout: 300
      runas: root
    - location: scripts/start_server.sh
      timeout: 300
      runas: root
  ApplicationStop:
    - location: scripts/stop_server.sh
      timeout: 300
      runas: root

Here's my stop_server.sh file under the scripts folder in my Angular root directory:

#!/bin/bash
isExistApp = `pgrep httpd`
if [[ -n  $isExistApp ]]; then
    service httpd stop        
fi

The error message that I get is "ScriptMissing" at the ApplicationStop step. The script is not missing. I stopped my codedeploy agent, tried to clear out the files under /opt/codedeploy-agent/deployment-root (but many were write protected), and restarted the codedeploy agent. No success after numerous attempts to get CodeDeploy to complete successfully. What should I do to get CodeDeploy working properly?"