[FarCry 3 patching problems]

@smashly Thank you!!!

It just solved my problem. Before this, i couldn't install any patch and now it works like a miracle. This is also a fix for those who get the message like "Not enough disk space" eventhough you have 100s of gigs of space remaining.

Long winded explanation of why your getting the message:
In most case receiving messages like "cannot obtain version number" means there are missing windows registry entries for the game.
All versions of official Far Cry 3 patches to this date do the same check in the windows registry.
The patch installer looks at 5 keys in the registry before it will install, if those 5 keys are not in the windows registry then the patch will fail to install usually throwing the message your seeing or other various messages about not being able to find the installed game.

The 5 keys in windows registry the patch looks for (in the order below):

1) Uninstall\{E3B9C5A9-BD7A-4B56-B754-FAEA7DD6FA88} "DisplayVersion"

2) Software\Ubisoft\Far Cry 3 "InstallDir"

3) Software\Ubisoft\Far Cry 3 "SKU"

4) Software\Ubisoft\Far Cry 3\GameUpdate "Info"

5) Software\Ubisoft\Far Cry 3\GameUpdate "InstallDir"

Providing the keys are present the patch will even install without even having the game installed.

Resolve to getting your patch to install:
Copy one of the text below that suites your OS into notepad and change 2 times "InstalDir" to the path of where your game is installed,
Make sure that you use "\\" in the path and not just a single "\".
Then Save As -> All Files -> FC3_101.reg, double click your new reg file, Yes/Ok when prompted:
Now try and install patch and see how you go.

For Win x64:

Windows Registry Editor Version 5.00
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Ubisoft\Far Cry 3]
"InstallDir"="C:\\Games\\Far Cry 3"
"SKU"="WW"
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Ubisoft\Far Cry 3\GameUpdate]
"InstallDir"="C:\\Games\\Far Cry 3"
"info"="ca32d7a363334a55b66633237b0335b7"
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{E3B9C5A9-BD7A-4B56-B754-FAEA7DD6FA88}]
"DisplayVersion"="1.01"

For Win x86:

Windows Registry Editor Version 5.00
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Ubisoft\Far Cry 3]
"InstallDir"="C:\\Games\\Far Cry 3"
"SKU"="WW"
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Ubisoft\Far Cry 3\GameUpdate]
"InstallDir"="C:\\Games\\Far Cry 3"
"info"="ca32d7a363334a55b66633237b0335b7"
 
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{E3B9C5A9-BD7A-4B56-B754-FAEA7DD6FA88}]
"DisplayVersion"="1.01"