change to this file were not saved to file system error in google chrome version 30.0.1599.101 m

Click on the cog in the developer tools window (lower right corner)

Go to workspace and add the directory which you would be working on.

This is to accidentally prevent you from modifying files that you did not intend on changing.

Happened to me too. After picking the workspace directory, I also mapped the file from the "Source" panel of Devtools to its filesystem equivalent (using right-click on the file, from the file tree). It solved my problem.

In chrome > 63, accepted answer option is disabled. In later should be done through workspaces.