Server becomes unregistered and remains in an "Initializing" state. Restarting the services does not resolve it.

Users are unable to launch applications from the affected VDA in this state, and they are unable to reconnect to disconnected sessions.

Found that the BrowserName for four applications had trailing spaces which was causing the VDA to go into an "OutofOrder" state. During tracing it was found that Database update/merge was failing due to this.

Remove the trailing spaces with the following Powershell commands:

Add Citrix snap ins in powershell before executing the below commands:

Add-PSSnapincitrix*
 
# Get a list of ApplicationNames and their associated BrowserNames.
 
Get-BrokerApplication-ApplicationName "*"|findstr"BrowserName ApplicationName" > C:\Apps.txt
 
# Use Apps.txt to find and correct each ApplicationName whose BrowserName contains a trailing space.
 
$app= Get-BrokerApplication-ApplicationName "{ApplicationName}"
Set-BrokerApplication-InputObject $app-BrowserName "{CorectedBrowserName}"
 
# For example:
#    $app = Get-BrokerApplication -ApplicationName "Application Name"
#    Set-BrokerApplication -InputObject $app -BrowserName "Application Name"
 

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Problem Cause

Incorrect applications "BrowserName" (which could include, not limited to, a trailing space at the end of the application browser name) is causing the VDA to go into an "OutofOrder" state. This is also causing database update/merge problems.

When the VDA is querying the Database it encounters an SQL exception (SQL error 8672) when it attempts to update the applicationInstance table with unexpected application instance data being queried. 

Error 8672: The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row. A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows.

This article helps solve an issue where the VDA goes into an Initializing state and unable to launch applications. Only a reboot of the machine fixes the issue.