Known issues

This article contains advisories and minor issues in XenServer 7.6 release and any workarounds that you can apply.


  • 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)

  • Do not assign more than 32 GB of memory to Dom0, as intermittent VM freezes can occur, often during boot of VMs. (CA-236674)


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

  • XenServer root passwords must not contain non-ASCII characters. (CA-47461)

  • In a Windows VM with XenServer Tools 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)


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

    When applying the XenServer 7.6 update to the XenServer 7.4 or 7.5 installation, you receive the error message “the server does not have enough space.” The error message appears because installation of the XenServer 7.6 update requires sufficient free space to avoid filling the disk, which is not possible with the legacy layout.

    When you receive this error, you cannot update to XenServer 7.6. You must perform a fresh installation instead. (CA-268846)

  • For customers on AMD hardware, you cannot live migrate a VM from a host running a previous version of XenServer to a host running XenServer 7.6. For example, while upgrading or updating hosts in a pool to XenServer 7.6.

    This issue is caused by a change in the AMD microcode level between the two versions of XenServer. For more information, see CTX237585 - Unable to live migrate VMs on AMD hardware.

    To work around this issue, shut down any VMs that you want to migrate from the older version of XenServer and restart the VMs after the host has been upgraded or updated to XenServer 7.6. (CA-293595)


  • Operations on all GFS2 SRs can get stuck if you have an IP address conflict (multiple hosts having the same IP address) on your clustering network involving at least one host with clustering enabled. In this case, the hosts do not fence. To fix this issue, resolve the IP address conflict. (CP-28758)


  • 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)
  • When XenCenter is installed on Windows Server 2008 SP2, it can fail to connect to a XenServer host with the message “Could not create SSL/TLS secure channel”. To resolve this issue, ensure that one of the following Windows Updates is installed on the Windows Server 2008 SP2 system: KB4056564 or KB4019276. For more information, see (CA-298456)


  • On XenServer hosts that use the bnxt_en driver, Oracle 6.x VMs can crash when connecting to a network. Ensure that your bnxt_en driver is up-to-date by installing the following driver disk: Driver Disk for Broadcom bnxt_en-1.8.29 - For XenServer 7.x CR. (CA-288010)
  • When installing the XenServer PV Tools, the XenServer PV Tools can request to restart with /quiet /norestart or /quiet /forcerestart specified after the VM has already been restarted once as part of the installation. (CA-290693)
  • Suspending or migrating a Linux VM with outstanding xenstore transactions can hang due to an issue in the VM’s Linux kernel. If your VM experiences this hang, force the VM to shut down and restart it. (CP-30551)

vSwitch Controller

  • When changing the IP address assignment mode from DHCP to static, you must restart the vSwitch Controller Virtual Appliance. (CA-293927)

Known issues