Mass Effect 3, for most of the world, is running on the latest version of 1.5. However, some users (so far, only the UK) have been reporting that version 1.6 exists and essentially makes them unable to use multiplayer. Friends with a mix of 1.5 and 1.6 will see a "You cannot play this game because your friend is using a different version of the game" message, or something similar when joing each other's lobby. In public games people will not be able to join and you will be unable to join unless the other players are on 1.6 as well. For the most part you will be soloing multiplayer.
How do I check if I have 1.6?
You can see this by looking at the file properties of Mass Effect 3 and looking at the details tab. You can find this file at <Mass Effect 3 Folder>\Binaries\win32\MassEffect3.exe
Or by using the Mass Effect 3 configuration utility, located at <Mass Effect 3 Folder>\Binaries\MassEffect3Config.exe:
Or looking at the file creation date, which for 1.5 is 1/10/2013, and for 1.6 is 9/13/2013.
The changes between 1.5 and 1.6 are unknown. There are no known patch notes and this build has only come to light recently.
What does this mean for me if I have this?
For singleplayer mods, probably nothing. The biggest impact is that in MP you cannot connect to users of 1.5 which is the vast majority of users.
How do I fix this and get 1.5?
I have made a package of my 1.5 install (vanilla) that you can install. It consists of my binaries folder (which contains MassEffect3.exe, the configuration utility, and the few .dll files it seems to use) and the Patch_001.sfar file that was built against that EXE. I don't know if the 1.6 and 1.5 versions of Patch_001.sfar actually are different.
You can download the 1.5 files here:
ME3 1.5 FILES: http://www.mediafire.com/download/1c5xf ... E3_1.5.zip
VIRUSTOTAL SCAN: https://www.virustotal.com/en/file/7b48 ... 456103024/
The scan shows 1 detection because the EXE is "likely encrypted", which is correct because MassEffect3.exe is encrypted in the original game installation. These files were not modified. These are the original Mass Effect 3 files from BioWare and require you to own the game on Origin in order to work.
Apply it by copying both folders over your Mass Effect 3 installation directory. You may consider backing up your Binaries and BIOGame/Patches folder first. It will overwrite some files.
You should then be showing 1.5.