This article is intended for Citrix administrators and technical teams only.
 
Non-admin users must contact their company’s Help Desk/IT support team and can refer to CTX297149 for more information.

When launching an application or desktop session using Citrix Workspace App, the session fails to launch with the error code “Your session 'AppName' did not launch successfully due to error code 3500. Please contact your administrator for more information about the error.”
Different reasons could cause this general error. This article includes common causes for this error and corresponding solutions.

Causes and Solutions

Please note that you have to load the Citrix PowerShell SnapIn before executing these commands.
Please run the following in the PowerShell window first:

Asnp Citrix*

Cause 1: For Multi-session OS machines, the VDA machine is reaching the maximum load you specified in one of following load management policies:

•  Maximum number of sessions
•  CPU usage
•  Disk usage
•  Memory usage
•  Memory usage base load

Solution 1: Please confirm if the VDA Server has reached the settings you specified in above HDX policies. This can be checked:

• Using Citrix Director: Trends => Load Evaluator Index tab.
• Using PowerShell:

Get-BrokerMachine |Select DNSName, LoadIndex, LoadIndexes

When troubleshooting the issue, please consider:

• Logging off idle or disconnected sessions 
• Increasing the number of VDA servers hosting the published resource to the Delivery Group.
• Resolving the performance issue on the VDA server if it is running into performance problems.

Cause 2: The Random single-session OS or multi-session OS machine the user is connecting to is in maintenance mode. 
Solution 2: Please turn off Maintenance Mode for that machine from Citrix Studio or PowerShell cmdlet:

Set-BrokerMachineMaintenanceMode -InputObject <domainname>\<hostname> $false

Cause 3: The user attempts to launch an app or desktop in Citrix Workspace app after access to the resource in the Delivery Group has been removed, but before the user has refreshed available apps in Citrix Workspace app.
Solution 3: 

• If Citrix Workspace app Self-Service Plug-in is disabled by Manage SelfServieMode policy , right click the Citrix Workspace app icon in Windows notification area and click Refresh.
• From the Citrix Workspace app, click the user name, in the dropdown list, and click Refresh Apps.

Cause 4: The VDA machine to host the HDX session is not registered to any of the Delivery Controller servers in the site.
Solution 4: Please refer to How to Troubleshoot Virtual Delivery Agent (VDA) Registration issues to resolve VDA registration issue. 

Cause 5: There are insufficient random/non-persistent Windows desktop VDA machines available for the user to successfully launch one.
Solution 5: Please power on more VMs in the Delivery Group or add more VDA machines to the Delivery Group.

Cause 6:  Pass-through authentication to Citrix Workspace app is attempted but the XML trust service is not correctly configured.
Solution 6: Please run the following PowerShell command as an administrator on the Delivery Controller:

Set-BrokerSite -TrustRequestsSentToTheXmlServicePort $True

Cause 7: SSL related registry settings under "HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\Wds\icawd" are rolled back to the default values after installing CU on VDA 1912 LTSR. (This is problem only when HdxSslEnabled is true on your delivery group.)
Solution 7: Please refer to Configure TLS on a VDA using the PowerShell script and enable TLS with "Enable-VdaSSL.ps1" on VDA. This is a bug addressed in 1912 LTSR CU4 as CVADHELP-17421.