Packer plugin protocol version negotiation and automatic upgrade behavior
Plugin version resolution at init time Packer 1.7+ uses a gRPC-based plugin protocol where the core negotiates a protocol major version at startup and rejects plugins advertising an incompatible major version. The packer init command resolves plugins declared in required_plugins blocks; when a version constraint uses a tilde ( ~> 1.2.3 ) or caret ( ^1.2.3