Citrix Hypervisor

Known issues

This article contains advisories and minor issues in the Citrix Hypervisor 8.2 release and any workarounds that you can apply.

General

  • If you host the Citrix License Server virtual appliance version 11.14 or earlier on your Citrix Hypervisor server, you see a warning when upgrading or updating to Citrix Hypervisor 8.2 Cumulative Update 1. The warning states that this virtual appliance is a PV VM that is no longer supported. You must uninstall this version of the Citrix License Server virtual appliance and instead install the latest version before upgrading or updating.

    The latest version of the Citrix License Server virtual appliance is available from the Citrix Licensing download page.

  • If your Citrix Hypervisor servers run on hardware containing Intel Sandy Bridge family CPUs, shut down and restart your VMs as part of updating or upgrading to Citrix Hypervisor 8.2 from Citrix Hypervisor 8.0 or earlier. For more information, see https://support.citrix.com/article/CTX231947. (CP-32460)

  • A pool’s CPU feature set can change while a VM is running. (For example, when a new host is added to an existing pool, or when the VM is migrated to a host in another pool.) When a pool’s CPU feature set changes, the VM continues to use the feature set which was applied when it was started. To update the VM to use the pool’s new feature set, you must power off and then start the VM. Rebooting the VM, for example, by clicking ‘Reboot’ in XenCenter, does not update the VM’s feature set. (CA-188042)

  • The increase in the amount memory allocated to dom0 in Citrix Hypervisor 8.0 can mean there is slightly less memory available for running VMs. On some hardware, you cannot run the same number of VMs with Citrix Hypervisor 8.2 as you can on the same hardware with XenServer 7.6 and earlier. (CP-29627)

  • When attempting to use the serial console to connect to a Citrix Hypervisor server, the serial console might refuse to accept keyboard input. If you wait until after the console refreshes twice, the console then accepts keyboard input. (CA-311613)

  • When read caching is enabled, it is slower to read from the parent snapshot than from the leaf. (CP-32853)

  • After upgrading to Citrix Hypervisor 8.2, when there is a lot of VM activity on a server in a pool that uses NFS storage, connections through ENIC to external storage can become temporarily blocked (5–35 minutes). VMs on that server can freeze and their consoles can become unresponsive. Attempts to ping in or out of the affected server subnet fail during these times. To fix this issue, install version 4.0.0.8-802.24 or later of the enic driver. For more information, see Driver Disk for Cisco enic 4.0.0.11 - For Citrix Hypervisor 8.x CR. (XSI-916)

  • When attempting to log in to the dom0 console with an incorrect password, you receive the following error message: When trying to update a password, this return status indicates that the value provided as the current password is not correct. This error message is expected even though it relates to a password change, not a login. Try to log in with the correct password.

  • If an Active Directory user inherits the pool admin role from an AD group that has spaces in its name, the user cannot log in to Citrix Hypervisor 8.2 CU1 through SSH.

    To work around this issue, you can do one of the following:

    • Rename this group in AD to remove the spaces from its name.
    • Create a new group in AD with the pool admin role and without spaces in its name. Add the user to this new group.

    In XenCenter, ensure that your new or renamed group is listed in the Users tab, either by adding or by removing and re-adding the group. Ensure that the user is associated with the new or renamed group. (CA-363207)

Graphics

  • When you start in parallel many VMs with AMD MxGPU devices attached, some VMs might fail with a VIDEO_TDR_FAILURE. This behavior might be due to a hardware limitation. (CA-305555)

  • When NVIDIA T4 added in pass-through mode to a VM on some specific server hardware, that VM might not power on. (CA-360450)

Guests

  • Citrix Hypervisor no longer supports VMs that run in PV mode. In previous releases, after upgrading your Citrix Hypervisor server to the latest version, these unsupported VMs might still run. However, in Citrix Hypervisor 8.2 CU1, PV mode VMs no longer start-up. Ensure that you remove any PV VMs from your pool or convert these VMs to HVM mode before upgrading to your pool to Citrix Hypervisor 8.2 CU1. (CP-38086)

  • If you install Debian 10 (Buster) by using PXE network boot, do not add console=tty0 to the boot parameters. This parameter can cause issues with the installation process. Use only console=hvc0 in the boot parameters. (CA-329015)

  • After a CentOS 8 VM with only one CPU is migrated to a new Citrix Hypervisor server, the first time a CPU-bound command runs on the VM, it times out. To work around this issue, you can assign more than one CPU to the VM and restart it. (XSI-864)

  • Some minor versions of Ubuntu 18.04 (for example 18.04.2 and 18.04.3) use an HWE kernel by default that can experience issues when running the graphical console. To work around these issues, you can choose to run these minor versions of Ubuntu 18.04 with the GA kernel or to change some of the graphics settings. For more information, see CTX265663 - Ubuntu 18.04.2 VMs can fail to boot on Citrix Hypervisor. (XSI-527)

  • If you attempt to revert a VM to a scheduled VSS snapshot that was created with Citrix Hypervisor 8.0 or earlier, the VM does not boot. The boot fails with the following error: This operation cannot be performed because the specified virtual disk could not be found. This failure is because the VSS snapshot capability has been removed from Citrix Hypervisor 8.1 and later. (CA-329469)

  • For domain-joined Windows 10 VMs (1903 and later) with FireEye Agent installed, repeated successful RDP connections can cause the VM to freeze with 100% CPU usage in ntoskrnl.exe. Perform a hard reboot on the VM to recover from this state. (CA-323760)

  • The guest UEFI boot capability provided in Citrix Hypervisor 8.0 was an experimental feature. Citrix Hypervisor 8.2 does not support migrating UEFI boot VMs created in Citrix Hypervisor 8.0 to Citrix Hypervisor 8.2. Shut down UEFI boot VMs before upgrading to Citrix Hypervisor 8.2 from Citrix Hypervisor 8.0. (CA-330871)

  • When UEFI-boot VMs start, they show a TianoCore logo. (CP-30146)

  • On Windows VMs, when updating the xenbus driver to version 9.1.0.4, ensure that you complete both of the requested VM restarts. If both restarts are not completed, the VM might revert to emulated network adapters and use different settings, such as DHCP or different static IP addressing.

    To complete the second restart, you might be required to use a local account to log into the Windows VM. When you log in, you are prompted to restart.

    If you are unable to log in to the Windows VM after the first restart, you can use XenCenter to restart the VM and complete the xenbus driver installation. (CP-34181)

  • When you create a UEFI VM, the Windows installation requires a key press to start. If you do not press a key during the required period, the VM console switches to the UEFI shell.

    To work around this issue, you can restart the installation process in one of the following ways:

    • In the UEFI console, type the following commands.

       EFI:
       EFI\BOOT\BOOTX64
      
    • Reboot the VM

    When the installation process restarts, watch the VM console for the installation prompt. When the prompt appears, press any key. (CA-333694)

  • On a Windows VM, after you have installed the version 9.x Citrix VM Tools for Windows, you might see both the previous and the latest version of the tools or management agent listed in your Installed Programs:

    • (PREVIOUS) Citrix XenServer Windows Management Agent
    • (LATEST) Citrix Hypervisor PV Tools

    The previous version of the management agent is not active and does not interfere with the operation of the latest version. We advise that you do not manually uninstall Citrix XenServer Windows Management Agent because this can disable the xenbus driver and cause the VM to revert to emulated devices.

  • On Windows 10 20H2 and later, Windows Update treats the latest xennet driver as a Manual Update and does not install it automatically. You can check the status of your driver installations by going to Windows Settings > Update & Security > View Update History > Driver Updates. If this occurs, you can install the driver by downloading the Citrix VM Tools for Windows from the Citrix Hypervisor download page, and installing manually the driver inside the MSI file. (CA-350838)

  • On a Windows VM, sometimes the IP address of an SR-IOV VIF is not visible in XenCenter. To fix the issue, restart the management agent from within the VMs Service Manager. (CA-340227)

  • On a Windows VM with more than 8 vCPUs, Receive Side Scaling might not work because the xenvif driver fails to set up the indirection table. (CA-355277)

  • When attempting to update a Windows 10 VM from 1909 to 20H2 or later, the update might fail with a blue screen showing the error: INACCESSIBLE BOOT DEVICE.

    To make it less likely that this failure occurs, you can take the following steps before attempting to update:

    1. Update the Citrix VM Tools for Windows on your VM to the latest version.
    2. Snapshot the VM.
    3. In the VM registry, delete the following values from the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\XENFILT\Parameters key: ActiveDeviceID, ActiveInstanceID, and ActiveLocationInformation

    This issue is still under investigation. (XSI-1075)

Installation

  • If you are using a legacy disk layout, the control domain has less space available to it than the current layout (4 GB vs 18 GB).

    In this case, when attempting to apply the Citrix Hypervisor 8.2 or Citrix Hypervisor 8.2 Cumulative Update 1 update to an earlier, you might receive the error message “the server does not have enough space”. This error happens because installation of the Citrix Hypervisor update requires sufficient free space to avoid filling the disk, which is not possible with the legacy layout.

    If you receive this error, you cannot update to Citrix Hypervisor 8.2 or Citrix Hypervisor 8.2 Cumulative Update 1. Do a fresh installation instead. (CA-268846)

  • When updating from Citrix Hypervisor 8.0 to Citrix Hypervisor 8.2, you might see the following error: Internal error: xenopsd internal error: Xenops_migrate.Remote_failed("unmarshalling error message from remote"). This error is seen if viridian flags were modified for a Windows VM existing when applying the hotfix XS80E003, but the VM was not shut down and restarted.

    To avoid this issue, before you try to update to Citrix Hypervisor 8.2, complete all steps in the “After installing this hotfix” section of the hotfix article for all Windows VMs hosted on a Citrix Hypervisor 8.0 server that has XS80E003 applied. (XSI-571)

  • If any vSwitch Controller state remains in your pool after an update or upgrade, clear the state with the following CLI commands:

     xe pool-set-vswitch-controller address=
     xe pool-param-set uuid=<uuid> vswitch-controller=
    

    (CA-339411)

  • Occasionally, booting a Citrix Hypervisor server from FCoE SAN using software FCoE stack can cause the host to stop responding. This issue is caused by a temporary link disruption in the host initialization phase. If the host fails to respond for a long time, you can restart the host to work around this issue.

  • When upgrading to or installing Citrix Hypervisor 8.2 from an ISO located on an IIS server, the install or upgrade can fail and leave your servers unable to restart. The remote console shows the GRUB error: “File ‘/boot/grub/i3860pc/normal.mod’ not found. Entering rescue mode”. This issue is caused by the IIS configuration causing package files to be missing. To work around this issue, ensure that double escaping is allowed on IIS before extracting the installation ISO on it. (XSI-1063)

  • [Fixed in the reissued Base Installation ISO - February 24, 2022] If your server has a NIC that requires the ice driver, this NIC is not available as part of the Citrix Hypervisor 8.2 CU1 installation process, as such you cannot configure it as the management interface or use it to retrieve installation files from a network server. Instead, use a different NIC during the installation process. (CA-363735)

Internationalization

  • Non-ASCII characters, for example, characters with accents, cannot be used in the host console. (CA-40845)

  • In a Windows VM with Citrix VM Tools for Windows installed, copy and paste of double-byte characters can fail if using the default desktop console in XenCenter. The pasted characters appear as question marks (?).

    To work around this issue, you can use the remote desktop console instead. (CA-281807)

Storage

  • If you use GFS2 SRs and have two servers in your clustered pool, your cluster can lose quorum and fence during an upgrade. To avoid this situation, either add a server to or remove a server from your cluster. Ensure that you have either one or three servers in your pool during the upgrade process. (CA-313222)

  • If you are using a GFS2 SR, ensure that you enable storage multipathing for maximum resiliency. If storage multipathing is not enabled, file system block writes might not fully complete in a timely manner. (CA-312678)

  • Citrix Hypervisor doesn’t support MCS full clone VMs with GFS2 SRs. (XSI-832)

  • If a Citrix Virtual Apps and Desktops or Citrix DaaS deployment with its VMs hosted on Citrix Hypervisor 8.2 uses multiple GFS2 SRs in a single MCS catalog, VMs in the catalog cannot access the VDIs during deployment. The error “VDI is currently in use” is reported. (XSI-802)

  • If you use HPE 3PAR hardware for your storage repository and, with a previous release of XenServer, you use ALUA1 for your host persona, when you upgrade to Citrix Hypervisor 8.2 multipathing no longer works. To work around this issue, migrate your host persona to ALUA2. For more information, see https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c02663749&docLocale=en_US.

  • After removing an HBA LUN from a SAN, you might see log messages and I/O failures when querying Logical Volume information. To work around this issue, reboot the Citrix Hypervisor server. (XSI-984)

  • You cannot set or change the name of the tmpfs SR used by the PVS Accelerator Supplemental Pack. When the type is tmpfs, the command xe sr-create disregards the value set for name-label and instead uses a fixed value. If you attempt to run the command xe sr-param-set to change the name of the tmpfs SR, you receive the error SCRIPT_MISSING.

  • You cannot run more than 200 PVS-Accelerator-enabled VMs on a Citrix Hypervisor server. (CA-365079)

Workload Balancing

  • During the Workload Balancing maintenance window, Workload Balancing is unable to provide placement recommendations. When this situation occurs, you see the error: “4010 Pool discovery has not been completed. Using original algorithm.” The Workload Balancing maintenance window is less than 20 minutes long and by default is scheduled at midnight. (CA-359926)

  • In XenCenter, the date range showed on the Workload Balancing Pool Audit Report is incorrect. (CA-357115)

  • For a Workload Balancing virtual appliance version 8.2.2 and later that doesn’t use LVM, you cannot extend the available disk space. (CA-358817)

XenCenter

  • Changing the font size or dpi on the computer on which XenCenter is running can result in the user interface appearing incorrectly. The default font size is 96 dpi; Windows 8 and Windows 10 refer to this font size as 100%. (CA-45514) (CAR-1940)

  • On Windows 10 (1903 and later) VMs, there can be a delay of a few minutes after installing the Citrix VM Tools before the Switch to Remote Desktop option is available in XenCenter. You can restart the toolstack to make this option appear immediately. (CA-322672)

  • It is not advisable to update the same pool from concurrent instances of XenCenter because this might disrupt the update process.

    If more than one instance of XenCenter is attempting to install multiple hotfixes on a pool, a server might fail to install a hotfix with the error: “The update has already been applied to this server. The server will be skipped.” This error causes the whole update process to stop. (CA-359814)

    To workaround this issue:

    1. Ensure that no other XenCenter instance is in the process of updating the pool
    2. Refresh the update list in the Notifications > Updates panel
    3. Start the update from the beginning
  • In XenCenter 8.2.3, importing an OVF or OVA file can be significantly slower than in earlier versions of XenCenter. (CP-38523)

Known issues