Citrix XenApp 7.6 Logon Slow - Long Black Screen Phase

Citrix XenApp 7.6 Logon Slow - Long Black Screen Phase
Update 2015-04-28: Citrix provides the limited release hotfix ICATS760WX64009 that fixes this issue. More information below. During the research for my session about the XenApp 7.6 logon process, to be presented at Citrix Synergy and BriForum London, I noticed that the logon to my XenApp 7.6 lab server was taking a bit long. Longer, in fact, than the combined durations of the main logon phases user profile loading, group policy processing, logon script execution and shell startup. Much longer. Also much longer than on an otherwise similar XenApp 6.5 machine.
Citrix/Terminal Services/Remote Desktop Services

Error Message Explained: User Profile Service Failed the Logon

Error Message Explained: User Profile Service Failed the Logon
This article is part of Helge’s Profile Toolkit, a set of posts explaining the knowledge and tools required to tame Windows user profiles. Many errors related to user profiles result in the user getting a temporary profile instead of the regular local or roaming profile. I have written about possible causes for that here. In addition to that, there is an entirely different category of errors that occur when even a temporary profile cannot be created. This article describes likely causes.
User Profiles

Folder Redirection - Denial of Service Waiting to Happen

Folder Redirection - Denial of Service Waiting to Happen
This article is part of Helge’s Profile Toolkit, a set of posts explaining the knowledge and tools required to tame Windows user profiles. One of the problems inherent to roaming user profiles is that they are copied to the local computer during logon. That takes time. Hence the motivation to limit the size of user profiles. One way of doing that is to put a quota on them, another one is folder redirection. Although widely used, redirection has its problems; problems so grave that Shawn Bass started to campaign against using folder redirection altogether. In this article I describe why Shawn despises redirection, which alternatives are available now what we can hope for in the future.
User Profiles

Taming Black Holes: Parallel Session Creation

Have you ever tried to log on to a terminal server and, after entering your credentials, been forced to stare at a grey screen for a lengthy period of time wondering what the machine might actually be doing? Of course you have, along with a few million other terminal server users. Being a technical guy (you would not be reading this otherwise) you have checked CPU / memory / hard disk utilization and the current session count when users complain that logons are slow. You will probably have noticed that all relevant metrics are in the green and logons are the slower, the more users try to log on to a server concurrently. It turns out that parallel logons are the root cause of the problem. Why?
Citrix/Terminal Services/Remote Desktop Services