We've just pushed another small update. This updated fixes some insecure code and a crash related to models. Read about it here.

It can take up to 15 minutes for updates to appear in Steam.

Fixed crash when rendering models with invalid flex rules
Fixed remote-code-execution exploit discovered by One Up Security

We've just pushed another small update. This updated fixes some insecure code and a crash related to models. Read about it here.

It can take up to 15 minutes for updates to appear in Steam.

Fixed crash when rendering models with invalid flex rules
Fixed remote-code-execution exploit discovered by One Up Security

We've just released a very small hotfix for the game. You can read about it here.
It might not appear in your Steam client for up to 15 minutes.

FIXED - Linux clients no longer crash on startup when a joypad is connected to the computer
UPDATED - gui.OpenURL now asks users for confirmation before opening a website

We've just released a very small hotfix for the game. You can read about it here.
It might not appear in your Steam client for up to 15 minutes.

FIXED - Linux clients no longer crash on startup when a joypad is connected to the computer
UPDATED - gui.OpenURL now asks users for confirmation before opening a website

Hey, we're pushing an update for Garry's Mod right now. You'll still be able to play on any servers that have not yet been updated.

There's some more in-depth information on the update here.

It might take up to 15 minutes for the update to pop up on Steam.

Game Changes

NEW - Preset support for Utilities menus
NEW - 'Quick Preset' button - allows for easier access to the preset system
NEW - Addons menu can now manage multiple addons at once (e.g. bulk unsubscribing)
NEW - Demos, saves, and duplications menus now list items that the user is subscribed to
NEW - Addons menu now has a search bar to quickly search through subscriptions
NEW - The '-notty' startup parameter on Linux servers will send console output directly to stdout
UPDATED - Weapons no longer turn upside-down when zooming in too far
UPDATED - Improved support for CS:GO/Portal 2/TF2 maps
UPDATED - Game returns to DirectX 9 mode if '-dxlevel' is not specified in the command-line
UPDATED - Improved relationships between Half-Life and Half-Life 2 NPCs
UPDATED - Improved behaviour of collisions between players and 'no collided' entities created by tools
UPDATED - Added more information to crash dumps (.mdmp files)
UPDATED - r_eyes_* console variables are no longer saved
UPDATED - The emitter tool's explosion effect no longer creates sounds
UPDATED - Bots can longer be created before the InitPostEntity hook has fired
UPDATED - Improved how serverside ragdolls are handled on the client - hull traces can hit them now
UPDATED - Updated the Half-Life Model Viewer to have newest features from Team Fortress 2 version
FIXED - Odessa no longer has female voices
FIXED - Fixed errors caused by the spawn menu's search feature not having access to certain directories
FIXED - Fixed many crashes related to NPCs trying to use non-existent entities
FIXED - Checkboxes and radio buttons in HTML panels are now displayed properly on Linux/macOS
FIXED - Half-Life Ichthyosaur can now cause damage
FIXED - Half-Life Tentacle NPC no longer continues playing sounds after being removed
FIXED - Fixed massive FPS drops when missing sounds are playing on servers
FIXED - Fixed crash that occurs when console variables created by Lua are removed too early on level change
FIXED - Fixed late loading of memory allocator on Linux causing the game to crash for some people
FIXED - Impulse 200 command no longer crashes when the player has no active weapon
FIXED - Fixed prediction errors when firing weapon_357
FIXED - weapon_357 now has the 'revolver' holdtype

Lua API Changes

NEW - Entity:PhysicsInitStatic( ... )
NEW - Entity:RemoveCallback( ... )
NEW - Entity:GetCallbacks( ... )
NEW - CLuaEmitter:IsValid( ... )
UPDATED - Entity:PhysicsInit* methods now return either true or false based on success
UPDATED - Entity:Remove() can no longer remove the world
UPDATED - Weapon:IsScripted() will now return false instead of no value when ran on non-scripted weapons
UPDATED - Player:Give( ... ) no longer fills a player's gun with ammo when asked to not give ammo to players
UPDATED - Entity:GetBoneCount() and Entity:GetBoneParent( ... ) will now return -1 on failure
UPDATED - Entity:TranslateBoneToPhysBone( ... ) will now return -1 on failure
UPDATED - Entity:SetSaveValue( ... ) now returns false on failure
UPDATED - Entity:DispatchTraceAttack( ... ) will now trigger an error when passed invalid parameters
UPDATED - Entity:HasBoneManipulations() and Entity:HasFlexManipulatior() return false on failure
UPDATED - Entity:GetBrushPlaneCount() will now return false on failure
UPDATED - Entity:GetFlexScale( ... ) now always returns 1 on failure, rather than just sometimes
FIXED - Entity:GetBrushPlaneCount() and Entity:GetBrushPlane( ... ) now work on brush entities
FIXED - PathFollower:Compute() no longer leaks Lua references

Hammer Changes

UPDATED - Improved performance of 2D/3D views
UPDATED - 2D views are now rendered during scroll operations, rather than after
UPDATED - Increased max render distance from 10,000 to 32,000
UPDATED - Vertices no longer need to be in the exact same location to be merged
FIXED - Blended textures are now rendered correctly - it should be identical to in-game
FIXED - Model browser no longer freezes after being opened multiple times
FIXED - Overlays no longer flicker when rendered in 3D shaded mode
FIXED - Scrollbars on 2D views are now correctly sized when zoomed in

GitHub Pull Requests

UPDATED - Removed CAP_INNATE_RANGE_ATTACK1 from weapon_base
UPDATED - Removed unused function parameters
FIXED - Result of COLLISION_GROUP_DEBRIS trace in properties.Gethovered is no longer ignored
FIXED - Fixed use of non-existent enum in DModelPanel
FIXED - Fixed 'Cannot set property' JavaScript error in main-menu
NEW - Trouble in Terrorist Town: Enabled scoreboard to be sorted by different criteria
UPDATED - Trouble in Terrorist Town: Corpses get skin/bodygroups of dead players
FIXED - Trouble in Terrorist Town: Fixed incorrect fall damage
FIXED - Trouble in Terrorist Town: Fixed 2 DoS exploits

Hey, we're pushing an update for Garry's Mod right now. You'll still be able to play on any servers that have not yet been updated.

There's some more in-depth information on the update here.

It might take up to 15 minutes for the update to pop up on Steam.

Game Changes

NEW - Preset support for Utilities menus
NEW - 'Quick Preset' button - allows for easier access to the preset system
NEW - Addons menu can now manage multiple addons at once (e.g. bulk unsubscribing)
NEW - Demos, saves, and duplications menus now list items that the user is subscribed to
NEW - Addons menu now has a search bar to quickly search through subscriptions
NEW - The '-notty' startup parameter on Linux servers will send console output directly to stdout
UPDATED - Weapons no longer turn upside-down when zooming in too far
UPDATED - Improved support for CS:GO/Portal 2/TF2 maps
UPDATED - Game returns to DirectX 9 mode if '-dxlevel' is not specified in the command-line
UPDATED - Improved relationships between Half-Life and Half-Life 2 NPCs
UPDATED - Improved behaviour of collisions between players and 'no collided' entities created by tools
UPDATED - Added more information to crash dumps (.mdmp files)
UPDATED - r_eyes_* console variables are no longer saved
UPDATED - The emitter tool's explosion effect no longer creates sounds
UPDATED - Bots can longer be created before the InitPostEntity hook has fired
UPDATED - Improved how serverside ragdolls are handled on the client - hull traces can hit them now
UPDATED - Updated the Half-Life Model Viewer to have newest features from Team Fortress 2 version
FIXED - Odessa no longer has female voices
FIXED - Fixed errors caused by the spawn menu's search feature not having access to certain directories
FIXED - Fixed many crashes related to NPCs trying to use non-existent entities
FIXED - Checkboxes and radio buttons in HTML panels are now displayed properly on Linux/macOS
FIXED - Half-Life Ichthyosaur can now cause damage
FIXED - Half-Life Tentacle NPC no longer continues playing sounds after being removed
FIXED - Fixed massive FPS drops when missing sounds are playing on servers
FIXED - Fixed crash that occurs when console variables created by Lua are removed too early on level change
FIXED - Fixed late loading of memory allocator on Linux causing the game to crash for some people
FIXED - Impulse 200 command no longer crashes when the player has no active weapon
FIXED - Fixed prediction errors when firing weapon_357
FIXED - weapon_357 now has the 'revolver' holdtype

Lua API Changes

NEW - Entity:PhysicsInitStatic( ... )
NEW - Entity:RemoveCallback( ... )
NEW - Entity:GetCallbacks( ... )
NEW - CLuaEmitter:IsValid( ... )
UPDATED - Entity:PhysicsInit* methods now return either true or false based on success
UPDATED - Entity:Remove() can no longer remove the world
UPDATED - Weapon:IsScripted() will now return false instead of no value when ran on non-scripted weapons
UPDATED - Player:Give( ... ) no longer fills a player's gun with ammo when asked to not give ammo to players
UPDATED - Entity:GetBoneCount() and Entity:GetBoneParent( ... ) will now return -1 on failure
UPDATED - Entity:TranslateBoneToPhysBone( ... ) will now return -1 on failure
UPDATED - Entity:SetSaveValue( ... ) now returns false on failure
UPDATED - Entity:DispatchTraceAttack( ... ) will now trigger an error when passed invalid parameters
UPDATED - Entity:HasBoneManipulations() and Entity:HasFlexManipulatior() return false on failure
UPDATED - Entity:GetBrushPlaneCount() will now return false on failure
UPDATED - Entity:GetFlexScale( ... ) now always returns 1 on failure, rather than just sometimes
FIXED - Entity:GetBrushPlaneCount() and Entity:GetBrushPlane( ... ) now work on brush entities
FIXED - PathFollower:Compute() no longer leaks Lua references

Hammer Changes

UPDATED - Improved performance of 2D/3D views
UPDATED - 2D views are now rendered during scroll operations, rather than after
UPDATED - Increased max render distance from 10,000 to 32,000
UPDATED - Vertices no longer need to be in the exact same location to be merged
FIXED - Blended textures are now rendered correctly - it should be identical to in-game
FIXED - Model browser no longer freezes after being opened multiple times
FIXED - Overlays no longer flicker when rendered in 3D shaded mode
FIXED - Scrollbars on 2D views are now correctly sized when zoomed in

GitHub Pull Requests

UPDATED - Removed CAP_INNATE_RANGE_ATTACK1 from weapon_base
UPDATED - Removed unused function parameters
FIXED - Result of COLLISION_GROUP_DEBRIS trace in properties.Gethovered is no longer ignored
FIXED - Fixed use of non-existent enum in DModelPanel
FIXED - Fixed 'Cannot set property' JavaScript error in main-menu
NEW - Trouble in Terrorist Town: Enabled scoreboard to be sorted by different criteria
UPDATED - Trouble in Terrorist Town: Corpses get skin/bodygroups of dead players
FIXED - Trouble in Terrorist Town: Fixed incorrect fall damage
FIXED - Trouble in Terrorist Town: Fixed 2 DoS exploits

Hey, we're planning to push the next Garry's Mod update next week on 2017-07-10. There's quite a lot of changes, so if you're running a server you'll probably want to at least try it out.

The update may not look like much, but I'm hoping that these internal changes are going to help us bring some more interesting updates in the future.

The Pre-Release Steam branch for Garry's Mod has been updated and contains all the changes that will be included in the next update. It is backwards compatible with the current version of the game, so if you are using it you'll still be able to connect to servers that haven't updated.

There will be instructions at the bottom of this post on how to join the Pre-Release branch.

Windows builds of the game now use the Visual Studio 2017 C++ Runtime. This should hopefully not affect anybody, but could perhaps break some third-party binary modules.

Linux builds of the game now depend on GLIBCXX 3.4.19. You may run in to some issues if your server's C++ runtime is a decade out of date. Steam should handle this for you if you're just playing the game.

Game Changes

NEW - Preset support for Utilities menus
NEW - 'Quick Preset' button - allows for easier access to the preset system
UPDATED - Weapons no longer turn upside-down when zooming in too far
UPDATED - Improved support for CS:GO/Portal 2/TF2 maps
UPDATED - Game returns to DirectX 9 mode if '-dxlevel' is not specified in the command-line
UPDATED - Improved relationships between Half-Life and Half-Life 2 NPCs
UPDATED - Demos, saves, and duplications menus can now list items that the user is subscribed to
UPDATED - Addons menu can now manage multiple addons at once (e.g. bulk unsubscribing)
UPDATED - Improved behaviour of collisions between players and 'no collided' entities created by tools
FIXED - Odessa no longer has female voices
FIXED - Fixed errors caused by the spawn menu's search feature not having access to certain directories
FIXED - Fixed many crashes related to NPCs trying to use non-existent entities
FIXED - Checkboxes and ratio buttons in HTML panels are now displayed properly on Linux/macOS
FIXED - Half-Life Icthyosaur can now cause damage
FIXED - Half-Life Tentacle NPC no longer continues playing sounds after being removed

Lua API Changes

NEW - Entity:PhysicsInitStatic( ... )
NEW - Entity:RemoveCallback( ... )
NEW - Entity:GetCallbacks( ... )
NEW - CLuaEmitter::IsValid( ... )
UPDATED - Entity:PhysicsInit* methods now return either true or false based on success
UPDATED - Entity:Remove() can no longer remove the world
UPDATED - Weapon:IsScripted() will now return false instead of no value when ran on non-scripted weapons
UPDATED - Player:Give( ... ) no longer fills a player's gun with ammo when asked to not give ammo to players
UPDATED - Entity:GetBoneCount() and Entity:GetBoneParent( ... ) will now return -1 on failure
UPDATED - Entity:TranslateBoneToPhysBone( ... ) will now return -1 on failure
UPDATED - Entity:SetSaveValue( ... ) now returns false on failure
UPDATED - Entity:DispatchTraceAttack( ... ) will now trigger an error when passed invalid parameters
UPDATED - Entity:HasBoneManipulations() and Entity:HasFlexManipulatior() return false on failure
UPDATED - Entity:GetBrushPlaneCount() will now return false on failure
UPDATED - Entity:GetFlexScale( ... ) now always returns 1 on failure, rather than just sometimes
FIXED - Entity:GetBrushPlaneCount() and Entity:GetBrushPlane( ... ) now work on brush entities
FIXED - PathFollower:Compute() no longer leaks Lua references

Hammer Changes

UPDATED - Improved performance of 2D/3D views
UPDATED - 2D views are now rendered during scroll operations, rather than after
UPDATED - Increased max render distance from 10,000 to 32,000
UPDATED - Vertices no longer need to be in the exact same location to be merged
FIXED - Blended textures are now rendered correctly - it should be identical to in-game
FIXED - Model browser no longer freezes after being opened multiple times
FIXED - Overlays no longer flicker when rendered in 3D shaded mode
FIXED - Scrollbars on 2D views are now correctly sized when zoomed in

Other Stuff

NEW - The '-notty' startup parameter on Linux servers will send console output directly to stdout
UPDATED - Added more information to crash dumps (.mdmp files)
UPDATED - r_eyes_* console variables are no longer saved
UPDATED - Explosion effect no longer creates sounds - this doesn't mean that explosions are silent
UPDATED - Bots can no longer be created before the InitPostEntity hook has ran
UPDATED - Improved how serverside ragdolls are handled on the client - hull traces can hit them now
FIXED - Fixed crash that occurs when console variables created by Lua are removed too early on level change
FIXED - Fixed late loading of memory allocator on Linux causing the game to crash for some people
FIXED - Impulse 200 command no longer crashes when the player has no active weapon
FIXED - Fixed prediction errors when firing weapon_357
FIXED - weapon_357 now has the 'revolver' holdtype

1. Exit the game
   
2. Right click on Garry's Mod in Steam and select Properties
   
3. Go to the Betas tab and select your desired branch

None - This is the normal version of the game
Pre-Release - This is the next update
Dev - This is a bleeding edge version of the game, expect it to contain more bugs than usual

If you want to set up an SRCDS instance using the Pre-Release branch, see this article: https://wiki.garrysmod.com/page/Hosting_A_Dedicated_Server.

Hey, we're planning to push the next Garry's Mod update next week on 2017-07-10. There's quite a lot of changes, so if you're running a server you'll probably want to at least try it out.

The update may not look like much, but I'm hoping that these internal changes are going to help us bring some more interesting updates in the future.

The Pre-Release Steam branch for Garry's Mod has been updated and contains all the changes that will be included in the next update. It is backwards compatible with the current version of the game, so if you are using it you'll still be able to connect to servers that haven't updated.

There will be instructions at the bottom of this post on how to join the Pre-Release branch.

Windows builds of the game now use the Visual Studio 2017 C++ Runtime. This should hopefully not affect anybody, but could perhaps break some third-party binary modules.

Linux builds of the game now depend on GLIBCXX 3.4.19. You may run in to some issues if your server's C++ runtime is a decade out of date. Steam should handle this for you if you're just playing the game.

Game Changes

NEW - Preset support for Utilities menus
NEW - 'Quick Preset' button - allows for easier access to the preset system
UPDATED - Weapons no longer turn upside-down when zooming in too far
UPDATED - Improved support for CS:GO/Portal 2/TF2 maps
UPDATED - Game returns to DirectX 9 mode if '-dxlevel' is not specified in the command-line
UPDATED - Improved relationships between Half-Life and Half-Life 2 NPCs
UPDATED - Demos, saves, and duplications menus can now list items that the user is subscribed to
UPDATED - Addons menu can now manage multiple addons at once (e.g. bulk unsubscribing)
UPDATED - Improved behaviour of collisions between players and 'no collided' entities created by tools
FIXED - Odessa no longer has female voices
FIXED - Fixed errors caused by the spawn menu's search feature not having access to certain directories
FIXED - Fixed many crashes related to NPCs trying to use non-existent entities
FIXED - Checkboxes and ratio buttons in HTML panels are now displayed properly on Linux/macOS
FIXED - Half-Life Icthyosaur can now cause damage
FIXED - Half-Life Tentacle NPC no longer continues playing sounds after being removed

Lua API Changes

NEW - Entity:PhysicsInitStatic( ... )
NEW - Entity:RemoveCallback( ... )
NEW - Entity:GetCallbacks( ... )
NEW - CLuaEmitter::IsValid( ... )
UPDATED - Entity:PhysicsInit* methods now return either true or false based on success
UPDATED - Entity:Remove() can no longer remove the world
UPDATED - Weapon:IsScripted() will now return false instead of no value when ran on non-scripted weapons
UPDATED - Player:Give( ... ) no longer fills a player's gun with ammo when asked to not give ammo to players
UPDATED - Entity:GetBoneCount() and Entity:GetBoneParent( ... ) will now return -1 on failure
UPDATED - Entity:TranslateBoneToPhysBone( ... ) will now return -1 on failure
UPDATED - Entity:SetSaveValue( ... ) now returns false on failure
UPDATED - Entity:DispatchTraceAttack( ... ) will now trigger an error when passed invalid parameters
UPDATED - Entity:HasBoneManipulations() and Entity:HasFlexManipulatior() return false on failure
UPDATED - Entity:GetBrushPlaneCount() will now return false on failure
UPDATED - Entity:GetFlexScale( ... ) now always returns 1 on failure, rather than just sometimes
FIXED - Entity:GetBrushPlaneCount() and Entity:GetBrushPlane( ... ) now work on brush entities
FIXED - PathFollower:Compute() no longer leaks Lua references

Hammer Changes

UPDATED - Improved performance of 2D/3D views
UPDATED - 2D views are now rendered during scroll operations, rather than after
UPDATED - Increased max render distance from 10,000 to 32,000
UPDATED - Vertices no longer need to be in the exact same location to be merged
FIXED - Blended textures are now rendered correctly - it should be identical to in-game
FIXED - Model browser no longer freezes after being opened multiple times
FIXED - Overlays no longer flicker when rendered in 3D shaded mode
FIXED - Scrollbars on 2D views are now correctly sized when zoomed in

Other Stuff

NEW - The '-notty' startup parameter on Linux servers will send console output directly to stdout
UPDATED - Added more information to crash dumps (.mdmp files)
UPDATED - r_eyes_* console variables are no longer saved
UPDATED - Explosion effect no longer creates sounds - this doesn't mean that explosions are silent
UPDATED - Bots can no longer be created before the InitPostEntity hook has ran
UPDATED - Improved how serverside ragdolls are handled on the client - hull traces can hit them now
FIXED - Fixed crash that occurs when console variables created by Lua are removed too early on level change
FIXED - Fixed late loading of memory allocator on Linux causing the game to crash for some people
FIXED - Impulse 200 command no longer crashes when the player has no active weapon
FIXED - Fixed prediction errors when firing weapon_357
FIXED - weapon_357 now has the 'revolver' holdtype

1. Exit the game
   
2. Right click on Garry's Mod in Steam and select Properties
   
3. Go to the Betas tab and select your desired branch

None - This is the normal version of the game
Pre-Release - This is the next update
Dev - This is a bleeding edge version of the game, expect it to contain more bugs than usual

If you want to set up an SRCDS instance using the Pre-Release branch, see this article: https://wiki.garrysmod.com/page/Hosting_A_Dedicated_Server.

An update has been released which fixes an issue that allows malicious clients to cause game-servers to crash. If you don't want this to happen to your server, you should update it.

All dedicated servers should be updated through either your Game Server Provider's control panel or SteamCMD.

Edit:
If it says 'content file is locked', contact Steam Support for help.
http://support.steampowered.com/

Your free antivirus is most likely deleting the game or update files causing it all to die. Add Steam to your AV exclusions, restart Steam, and try updating again.

An update has been released which fixes an issue that allows malicious clients to cause game-servers to crash. If you don't want this to happen to your server, you should update it.

All dedicated servers should be updated through either your Game Server Provider's control panel or SteamCMD.

Edit:
If it says 'content file is locked', contact Steam Support for help.
http://support.steampowered.com/

Your free antivirus is most likely deleting the game or update files causing it all to die. Add Steam to your AV exclusions, restart Steam, and try updating again.