Environment named ****** is in an invalid state for this operation.

I've got exactly same issue. Using the stats command I see STATUS = READY but deploy keep failing.

This issue started after I've cloned the environment and later deleted the cloned one and left the original.

I have found this issue is because some Elastic Beanstalk scheduled actions: A scheduled action set the environment without instances. This is ok. The second one scheduled action set the environment with the default autoscaling policy (1 instance running, 1-4 required instances). This last one has been failing on rebuild environment or update environment.

If I configure it into the autoscaling group, will work all except rebuild environment where I have to delete the scheduled actions in order to rebuild the environment.

Shouldn't EB allow or recreate the scheduled actions on rebuild environment?

Looks like one of my environments is receiving the same error message that you identified at the start of this thread ("Must be Ready"). However, the status of the environment according to the app IS Ready.

I am currently unable to deploy new application versions, or make configuration changes to the environment as AWS Elastic Beanstalk returns the same error message each time. "Environment named XXXXXX is in an invalid state for this operation. Must be Ready."

I have checked for scheduled updates and reviewed the environment configuration like you did above. Last resort looks like an environment rebuild to clear out whatever error AWS is getting caught on.

Was this the last step that you took to correct everything? Do you have any advice on what to look for or avoid during the rebuild?

Thanks.