- Plesk Onyx for Linux
The following error appears in an attempt to create a Docker environment variable with lowercase letters:
PLESK_ERROR: The name of an environment variable can consist solely of uppercase letters, digits, and the underscore ('_'), and cannot begin with a digit.
#EXTDOCKER-23 " Names of environment variables can now contain lowercase letters. "
- Docker 1.4.0 18 October 2018 (Linux)
If update is not possible for some reason you may try the following