When I encountered this error, I checked the “Details” job, and saw that it was “Missing resource” next to Execution Environment. Then I looked at the project that should have been pulled/updated and that task failed, which I guess lead to the EE missing and the the error in the actual task.
yup had that similar error.
It was caused due to python, galaxy dependencies. you need to add dependencies inside execution environment and then add that EE in your org, project and templates.
these links can help you.