Help us track down an elusive bug in the Roblox installer

Hi Developer Community!

As many of you probably know, the Client and Studio aren’t the only applications we make at Roblox - we also make a small utility called the Roblox Installer, whose job it is to ensure that the Client and Studio are up-to-date every time you click on the Play button.

For the majority of our users this works fine, and you hardly ever notice it (ok, ok, once a week when we release a new version you’ll notice it…), but because it has to run reliably on every version of Windows back to Xp, it’s hard for us to test every scenario, so there are some error cases that we just can’t anticipate.

For the last couple of weeks we’ve been trying to track down one elusive error, but so far to no avail, so I’m asking for information from anyone whose experienced the issue.

The error in question manifests itself as a message box popping up when you try to install with an error message along the lines of

CreateProcess C:\Users\USERNAME\AppData\Local\Temp\RBX-C0E860FA.tmp failed: %1 is not a valid Win32 application."

This means that something has gone wrong when we tried to download a new version of the installer, but we didn’t detect it, so we tried to launch what we downloaded, but for some reason the file was invalid.

If anyone has experienced this issue, then it would be really helpful to know the size of the file that CreateProcess tried to launch, and if you could open it in notepad for example, also paste the first line of text (it’s most likely going to be garbage, but I want to see if it’s a proper executable or perhaps a HTML error message). It would also be incredibly helpful if you could send me the installer log file in a private message (it should be in your C:\Users\USER_NAME\AppData\Local\Temp folder, called RBX-EIGHT_LETTERS_AND_NUMBERS.log).

Thanks a bunch!


I had that problem a lot at my High School last year. They fixed it by whitelisting some of the code signature from the downloaded files. The internet was blocking it due to thinking it was malicious. The change also fixed every computer connected to their wifi, including my own laptop from home.

I believe the problem is that the installer tries to download some different files from different locations, some of which are blocked by the user’s firewall or internet security, or the files themselves might be blocked to due false flagging.

In addition, sometimes when the game would update and a lot changed, it would get blocked again, so the code signature had to be updated on the security software to fix it again.

EDIT: I also just remembered that we were able to fix it on a case by case basis by switching the DNS server. They had just set up a new DNS system at the time, and switching to that new one would fix the problem. They hadn’t updated the image on the machines, so we had to change it manually every time. The issue was there 100% of the time before and fixed 100% of the time after.

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Ah, interesting, thanks.

That does explain why none of our attempts to fix the issue have succeeded (we’ve added lots of integrity checks and retries, so we’re pretty confident that when we do try to launch the executable it does match byte-for-byte what we expect), but it also means that we need to try to figure out a way to detect if this is happening, and give a better error message.

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