Possible Causes for this problem found.
This may or may not have anything to do with the problem some people have installing vCenter and Horizon View but I'm going to throw it out there because I had the problem and now I don't. I've installed Horizon View on three of my accounts and all went fine except when I tried on my own server in my office and I got the error in this blog. After getting the error, I went down the same path as others where I installed Single Sign On first, got the error, fixed the error using the "ssocli configure-riat -a discover-is --simulate -u admin (Remove “–simulate” to apply)" command line then proceeded to install Inventory Service and vCenter to complete the install. What happened next helped me figure out what "may" be causing the "Error 29155. Identity source discovery error" issue. I accidentally overwrote my host that was not only running my Horizon View install but also it had my second domain controller on it. In order to rebuild the domain controller I had to do all the steps to purge it in AD, DNS as well as NTDSUTIL to verify it was gone. While I was in NTDSUTIL I noticed there was an old skeleton of a domain controller I had forgotten existed so I removed it as well and also cleaned DNS, AD Sites and Services, etc. After all said and done I had a very clean DS and a new secondary domain controller up and running and was ready to do the Horizon View install again. This time I didn't get the error though. So, "maybe" this error has something to do with the fact that I had old remnants of DNS and AD skeletons hanging around and for the most part was a mess. On all of my client networks I've had no problems and never got the error and they all have very clean DS/DNS etc. My network, on the other hand, has been around since the early 2000's and I haven't really worried about keeping it clean through the upgrades. This may or may not be the issue behind this error but this is what happened to me so I thought I’d post it and see if it helps anyone else. Check your AD and DNS and make sure all is current and clean before you install and you may not get this error. As always, please take this post with no warranties and at your own risk.