Stage name issue after deployment

Serverless Framework
1

In the serverless.yml file, I was using interpolation to generate stage value. And I got the following errors after running sls deploy.

# serverless.yml
provider:
  name: aws
  runtime: nodejs6.10
  memorySize: 512
  timeout: 30
  stage: ${self:custom.CONFIG.STAGE, 'dev'} 
  region: ${self:custom.CONFIG.REGION}
custom:
  CONFIG: ${file(config.yml):env}

# config.yml
env:
  STAGE: dev
  REGION: ap-southeast-2

# Error log 
Serverless: 'Too many requests' received, sleeping 5 seconds
Serverless: 'Too many requests' received, sleeping 5 seconds
Serverless: 'Too many requests' received, sleeping 5 seconds
 
  Serverless Error ---------------------------------------
 
  Stage name only allows a-zA-Z0-9_

This error can be fixed by using static values like ‘dev’ or ‘production’.

2

Can you include your config.yml?

3

Just updated. Actually, it might not be caused by the file config.yml, coz even I change it to stage: ${opt.stage, 'dev'}, the error still can be reproduced. But using stage: dev works well.

4

Did you mean ${opt.stage, 'dev'} because it should be ${opt:stage, 'dev'}

5

Yes, that was a typo. It should be ${opt:stage, 'dev'}. Even the using the correct syntax, I still keep getting same error.