一、网络环境问题：

1. gclient Failed to download the file, check your network connection, 使用“2”个参数调用“DownloadFile”时发生异常:“在 WebClien t 请求期间发生异常。”

解决方案：

设置自己的代理

set http_proxy=http://localhost:7890
set https_proxy=http://localhost:7890

Your current directory appears to already contain, or be part of,
a checkout. "fetch" is used only to get new checkouts. Use
"gclient sync" to update existing checkouts.

Fetch also does not yet deal with partial checkouts, so if fetch
failed, delete the checkout and start over (crbug.com/230691).

解决方案：

由于中国网络导致下载失败。重新fetch提示错误。问题在于fetch.py的Checkout::exists判定了depot_tools.gclient, depot_toolssrc,depot_tools.gclient是否存在。如果存在删除了就可以重新开始。

1. fetch chromium中间网络断掉或者出现错误

解决方案：gclient sync --force

1. Error: Command 'git rev-list -n 1 HEAD' returned non-zero exit status 128

解决方案：删除报错目录下的.git文件夹

1. Hook 'python3 src/build/download_nacl_toolchains.py --mode nacl_core_sdk sync --extract' took

解决方案：更新depot_tools，执行update_depot_tools.bat在Windows或./update_depot_toolsLinux或Mac上运行

1. returned non-zero exit status 1

解决方案：执行gclient runhooks

7、Exception: dbghelp.dll not found in "C:Program Files (x86)Windows Kits10Debuggersx64dbghelp.dll"
You must install Windows 10 SDK version 10.0.20348.0 including the "Debugging Tools for Windows" feature.
ERROR at //build/toolchain/win/BUILD.gn:24:3: Script returned non-zero exit code.

解决方案：打开控制面板 → 程序 → 程序和功能 → 选择“Windows Software Development Kit” → 更改 → change → 勾选上“Debugging Tools For Windows” → change