When you try to push your application to Cloud Foundry with "cf push" command, it may fail with the error message as follows:
Downloading build artifacts cache...
Downloading app package...
Downloaded app package (1.2M)
BuildpackCompileFailed - App staging failed in the buildpack compile phase
FAILED
You do not see what exactly the problem is from the displayed messages.
Solution
There are many possibilities of errors. You can get useful information for your investigation from a log by calling a command:
cf logs YOUR_APPLICATION –recent
*Replace YOUR_APPLICATION with your application name.
Here is an example output when you added an unexpected character in package.json file:
2021-05-07T19:07:19.11+0100 [STG/0] OUT **ERROR** Unable to load package.json: invalid character 'a' after object key:value pair
Notes
Please refer to following page to learn more about application logging with Cloud Foundry
https://docs.cloudfoundry.org/devguide/deploy-apps/streaming-logs.html