运行环境：mac os 10.12

当我想获取微信的 contexts 或者切换 webview 时，缓冲运行 1 分钟，会报错。

脚本错误：

WebDriverException:
Error: None
Message: no such session
(Driver info: chromedriver=2.20.353124 (035346203162d32c80f1dce587c8154a1efa0c3b),platform=Mac OS X 10.12.3 x86_64)

服务器错误：

chromedriver bin path: /usr/local/lib/node_modules/macaca-android/node_modules/._macaca-chromedriver@1.0.30@macaca-chromedriver/exec/chromedriver
Starting ChromeDriver 2.20.353124 (035346203162d32c80f1dce587c8154a1efa0c3b) on port 9515
Only local connections are allowed.
chromedriver starting success.
chromedriver ready with: {"sessionId":null,"status":100,"value":{"message":"chrome not reachable\n (Driver info: chromedriver=2.20.353124 (035346203162d32c80f1dce587c8154a1efa0c3b),platform=Mac OS X 10.12.3 x86_64)"}}
也就是 chrome not reachable
我查阅了源码里没有 no such session 这个 erro 定义。
请问如何才能修复呢