I'm having the same problem, already delete putenv but still same.
[ErrorException]
Undefined index: process
install [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-suggest] [--no-dev] [--no-autoloader] [--no-scripts] [--no-progress] [--no-install] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--apcu-autoloader-prefix APCU-AUTOLOADER-PREFIX] [--ignore-platform-req IGNORE-PLATFORM-REQ] [--ignore-platform-reqs] [--] [<packages>]...
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