Waiting for another flutter command to release the startup lock…

出现此问题，说明有另一个flutter进程正在运行，耐心等待Downloading...

或者重启电脑即可。

出现问题场景：

当点击Flutter upgrade时，Flutter进行升级，进行相关下载操作。如果此时关闭Android studio或者中断下载，执行Flutter操作就会出现Waiting for another flutter command to release the startup lock…，等待下载完毕即可。