6.0.10
March 15, 2017
Fixed
Use legacy notifications by default on all Windows devices. Looks like the freezing issue on previous builds was caused by native notifications instead of Sass. My apologies to Sass for wrongful conviction.
6.0.9
March 15, 2017
Fixed
Freezing issue while compiling sass files.
6.0.8
March 02, 2017
Fixed
Crash while compiling some less files with errors.
6.0.7
March 01, 2017
Fixed
Private key parsing error while uploading files via SFTP.
Fixed
Crash while compiling some stylus files.
Updated
Autoprefixer 6.7.6
Updated
Node Sass 4.5.0
Updated
Ruby Sass 3.4.23
Updated
UglifyJS 2.8.3
6.0.6
Jan 24, 2017
Fixed
Live Preview not working due to a port assignment error.
Updated
Typescript 2.1.5
Updated
Autoprefixer 6.7.0
Updated
Cssnext 2.9.0
Updated
Node Sass 4.3.0
Updated
Less 2.7.2
Updated
Babel Dependencies
babel-core -> 6.22.1
babel-plugin-syntax-jsx -> 6.18.0
babel-plugin-transform-async-to-generator -> 6.22.0
babel-plugin-transform-class-properties -> 6.22.0
babel-plugin-transform-object-rest-spread -> 6.22.0
babel-plugin-transform-react-jsx -> 6.22.0
babel-preset-es2015 -> 6.22.0
Updated
Electron and other internal dependencies
6.0.5
Dec 25, 2016
Fixed
Import error while compiling sass files
Fixed
Crash when server port is larger than 60000
Fixed
Port not changing even when assign new port option is selected
6.0.4
Dec 13, 2016
Fixed
FTP marking some not-deleted files as deleted.
6.0.3
Dec 12, 2016
Fixed
SFTP username field not showing.
Fixed
Error while compiling files with ruby sass, slim and haml.
Fixed
File watcher config not being saved properly.
Added
Context menu option to watch/filter file extensions.
Updated
Updated node-sass to 4.0 and LibSass to 3.4
6.0.2
Dec 09, 2016
Added
Select multiple files in file tree.
Added
Option to disable compile success and error notifications.
Added
Option to use legacy notifications instead of native notifications.
Fixed
Keyboard navigation not working in some cases.
Fixed
Crash on Linux while changing output path.
Fixed
Crash while changing FTP settings.
Fixed
Autoprefixer settings not working properly.
Improved
Icon rendering on Windows system tray.
6.0.1
Dec 02, 2016
Fixed
File Watcher not working on Dropbox or any other folder with parenthesis on name.
Fixed
Live reload not working with CSS and JS files with auto compile.
Fixed
Live Reload not working with imported jade files.
Fixed
Image optimization not working on macOS.
6.0.0
Nov 29, 2016

Prepros 6 is rewritten from ground up with performance and stability in mind.There are a lot of under the hood changes and improvements. Some notable features are listed bellow.

Added
Typescript Support
Added
Babel, React JSX and Babel Plugins Support
Added
New UI as well as Dark & Light Themes
Added
Pug language support. (Pug is newer version of jade).
Added
Mix compilers to change compile tasks
Added
Build & Export.
Added
New Logger to find out exactly where a error is in a file.
Added
Linux Debian installer.
Improved
Live Reload with cross browser support.
Improved
Browser Sync with cross browser support.
Improved
Latest version of all compilers.
Improved
It takes less than a second to add projects now.
Removed
Compass support. (Compass has been discontinued by it's developers.)

There are a lot of changes not listed here. Please download and use Prepros to find out ;)