"Installer integrity check has failed." over and over again.

Unity Engine
1

Since Monday morning, 2+ days, I’m downloading and attempting to install the current Unity Free Edition for Windows, version 3.5.5, UnitySetup-3.5.5.exe. Windows Pro x86-64.

  • The download of the installer finishes without error messages, 509MB. Wrong file size? I do not use download managers, etc.
  • But when I check the download with 7-zip I get umpteen error messages (see screenshot).
  • When I’m firing up the installer anyway, with “Run as Administrator”, I get a popup titled “NSIS Error” (see screenshot).
  • I also tried installing from an elevated command prompt with the no CRC check argument /NCRC, a tip which I picked up from the net. That will skip the check and start the installer, the installer then uninstalls the previous version, but quite short after the uninstall quits with an error about a corrupted installer. Wicked tip. Way to go!
  • I tried with my desktop (Windows, wired), notebook (Windows wired+wireless), Macbook Pro (wrired+wireless), Mac Mini.
  • To rule out routing issues at my ISP’s end, I downloaded with wget (to my server at Incero llc), then checked the download with the command line version of 7-zip (p7zip) on the server. But it was also reporting bad files.
  • I repeated the above for what feels like a million times already.
  • For comparison, I re-downloaded my Adobe Creative Cloud subscription to my PC without any errors. This is a multi-gigabyte download.
  • I tried last evening at a friends house. And got the same result.
  • I even took my notebook to the public library in a last attempt. But got the same result.

The “funny” bit is that the file sizes of the downloads are identical in bytes. But the files (inside the downloads) reported as bad are different every download. See screenshots.

While I’m typing this I’m re-downloading again to my desktop PC. But it will be the last attempt.
Like they say. It borders on insanity to expect a different result, when repeating the same thing over and over again, without changing anything.

Bottom line. I have no working Unity installation anymore since early Monday morning.
Back to my work because Unity is not making me any money, and my web design and development projects do.

2

Problem resolved. By coincidence.
I had a problem with my Anti Virus and bumped into a thread detailing the problem at their support forum.
Too little too late for me, because I’m not using Unity anymore.
But it might help others.

The download corruption problem occurs when at least 1 of 2 Microsoft Windows 7 hotfixes were installed in combination with Eset NOD32 Antivirus.
Eset claims that it is caused by MS, but I have my doubts. No other Anti Virus software is reported to cause the download corruptions in combo with these 2 hotfixes. But make up your own mind.

After reading the 2 threads I first attempted another Unity download with both hotfixes and Eset NOD32 installed. Result : download corruption.
Then I uninstalled NOD32 with their cleaner tool. Rebooted and downloaded Unity. Result : download 100% OK. Checked with WinRAR and 7-zip. I could install Unity without any problem.
(I can’t explain why the download from Adobe’s site, which I mentioned in my previous post, did download OK though.)
So I uninstalled Unity, re-installed NOD32, and tried downloading Unity again. Result : download corruption.

The thread at the official Antiviris Support forum : Beware of MS hotfixes KB2735855 and KB2750841
And the thread at Microsoft Answers : kb2735855 causes my downloads to break

I wish everybody in the Unity Community good luck and fortune with their projects.

3

Just use the /NCRC flag in the command prompt.