An update has been released for Left 4 Dead 2.

- Fixed several rare but persistent crashes:
- Round restart in No Mercy map 1
- Witch eye glow particle system
- Chainsaw pose parameter update
- Common Infected post data update
- Scavenge mode scoreboard
- Fixed text input not working correctly in Hammer model browser search field.

An update has been released for Left 4 Dead 2.

- Fixed a file management bug that could cause some users to run out of memory when opening the Addons screen.
- Removed SSE2 requirement that was added during the Linux port.
- Fixed plugin handler reporting all commands as coming from the server, even when they came from the client.

This update also include an update to the L4D2 Authoring Tools

- Added the Extended Mutation System
- Included demo EMS modes Holdout, Dash, L4D1
- Added support for Linux

- Server operators can now specify whether or not custom content is allowed when playing on their servers. This can be set on a per game mode basis – see cfg/addonconfig.cfg for details.

- Fixed yellow screen corruption that occurs on AMD Radeon HD 6000 Series hardware.
- Updated database to include video cards from the Steam survey through April 2013.

Add-ons
- If a found game is using a Mutation add-on from the workshop, the "Download Add-on" button will open the workshop page
- Adjusted add-on sorting when loading the main menu so Mutation add-ons can override UI elements.
- Reworked add-on management to improve stability and properly support custom mutations.
- Fixed the download progress panel sometimes not updating because it was referencing a different file than the one currently downloading.
- Added a drop-down menu to the add-on screen to filter by tags.
- Fixed occasional focus problem when clicking on the Addons list panel.
- Allow keyboard scrolling of the Addons list panel.

Publishing Tools
- Fixed published file browser not updating after publishing new content.
- Fixed published file browser showing only the first fifty items of a users workshop.
- Fixed upload tool throwing an error when replacing an existing file, if the file size was greater than the available space in the cloud.
- Fixed upload tool sometimes showing an error dialog for files that had been deleted from workshop.

Changes:
- Fixed a possible buffer overflow in keyvalues
- Fixed player_death event setting "victimname" to "Charger" when the Spitter gets killed.
- Fixed a bug that sometimes caused the rescue vehicle to arrive immediately when the second team in a versus match started the finale.

Left 4 Dead 2 Workshop Manager
- Updated scheme
- Added new tags
- New field for change notes when editing existing workshop items

- Added support for dedicated servers to load addons from the "workshop" subdirectory. Fixes consistency errors when playing workshop campaigns on dedicated servers.

NOTE TO SERVER OPERATORS: To host workshop campaigns on your dedicated server, they should now be placed in the same location as on the client (/left4dead2/addons/workshop/…) Campaigns not downloaded from the workshop can still go in the "addons" directory.

Custom Campaign select screen:
- Show all installed custom campaigns, not just the ones that support the current mode.
- Disable list items for campaigns that don't support the current mode, and sort them to the bottom of the list.
- Fixed some uninitialized text fields when no campaign is selected.
- Moved an informational string so it doesn't overlap the campaign list.

Workshop Publishing Tool:
- Removed the file count from the download progress bar to avoid confusion when stale meta-data indicates there are more files than actually exist.
- Don't show the download progress bar if no valid files were found.
- Fixed the "Failed to write file chunk…" error message not correctly showing the number of bytes written.

- Fixed Workshop add-ons not mounting correctly on the Mac

- Updated a Steam binary that may have been causing some Windows Dedicated Servers to crash

• Workshop now available for Left 4 Dead 2.
• Added Workshop Manager upload tool to Left 4 Dead 2 Authoring Tools.
• Add-ons screen now supports browsing the workshop and subscribing to workshop content.
• Moved add-on menu option to main menu
• Added the ability to filter add-on content by tags.
• Fixed scoreboard not showing the campaign name for custom campaigns.
• Fixed "Rescue" label not drawing correctly in the scoreboard for campaigns with more than five maps.
• Cleaned up DLC add-on file dependencies and simplified talker file structure - the manifest has changed.
• Fixed an issue where some L4D1 vocalizations that were also present in L4D2 weren't firing.
• Fixed transition dialog in L4D1 campaigns.
• Various fixes for character dialog including conversations, weapon spotting, defibs, and other misc audio.
• Added data on L4D1 characters so corresponding Talker rules would work (ie Elevator Speech in No Mercy)