This is a config file from 0.14 and you're trying to load it in 0.15.
From the 0.15.0 changelog:
Configuration
- Configuration has been reset.
Since 0.15 Factorio checks if the first line is
If it's not, then the config is invalid and has to be regenerated. You can workaround this by adding that line as the first line yourself, but this is not recommended.
In 0.15 all settings that are at default are commented out with a semicolon, and if you use a modified 0.14 config then changes in the defaults won't apply to you, e.g. if they decide to switch the default keybinding of a key to another one or change default graphics settings it won't change for you.
Also, in 0.14 configuration files some of the names (especially in [sound], [debug] and [other]) used the _ (underscore) as delimiter, in 0.15 they all use the - (hyphen). This will reset some of your settings, especially the settings found in Settings --> Other anyway, so it's probably better to reset the config and use the in-game Settings dialog to reconfigure your settings.