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 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. This behavior has been improved for sequential reads, but not for other types of read. (CP-32853)

  • 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. The warning states that this virtual appliance is a PV VM that is no longer supported.

  • (Fixed in Workload Balancing 8.2.1) When multiple VMs start at the same time, Workload Balancing recommends balancing the VMs placement on all servers in the pool evenly. However, sometimes Workload Balancing might recommend putting many VMs on the same Citrix Hypervisor server. This issue occurs when Workload Balancing gets late feedback from XAPI about VM placement. (CA-337867)

  • 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)

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)

Guests

  • 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-329435)

  • 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)

  • (Fixed in Citrix VM Tools for Windows 9.2.1) 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, 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)

  • (Fixed in Citrix VM Tools for Linux 7.20.1-1) If you attempt to install the Citrix VM Tools for Linux on a fully up to date CentOS 8 system, you see the error: Fatal Error: Failed to determine Linux distribution and version. This is caused by changes in that CentOS 8 updates release on Dec 08, 2020. To workaround this issue, specify the OS when installing the Citrix VM Tools for Linux: ./install.sh -d centos -m 8. However, if you use this workaround, the operating system information is not reported back to the Citrix Hypervisor server and does not appear in XenCenter. (CA-349929)

Installation

  • If you have previously upgraded your Citrix Hypervisor 8.0 installation from XenServer 6.5 or earlier, with virtual machines using the server’s “Local Storage” storage repository, or if a vendor utility partition is present on your disk, you are using a legacy disk layout. The legacy disk layout means the control domain has less space available to it than the current layout (4 GB vs 18 GB)

    When attempting to apply the Citrix Hypervisor 8.2 update to the Citrix Hypervisor 8.0 installation, you receive the error message “the server does not have enough space”. This error happens because installation of the Citrix Hypervisor 8.2 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. 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)

  • 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 workaround this issue, ensure that double escaping is allowed on IIS before extracting the installation ISO on it. (XSI-1063)

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)

  • 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.

  • (Fixed in Hotfix XS82E006) When IntelliCache is enabled on your Citrix Hypervisor server and you attempt to start a VM, the action might fail with the message “VDI not available”. This failure occurs when the cache SR is out of space, but caching is not disabled. To work around this issue, manually disable caching or increase the space on the cache SR. (CA-340619)

  • 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)

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)

  • (Fixed in XenCenter 8.2.3) If you have FIPS compliance enabled on the system where XenCenter is installed, you cannot import or export VMs in OVF/OVA format or import Virtual Hard Disk images. (CA-340581)

Known issues