Microsoft Exchange 2013/ 2016/ 2019 shows blank ECP & OWA after changes to SSL certificates

This issue is described in KB2971270 and is fixed in Exchange 2013 CU6. I published this blog post in July 2015 and it is still relevant. The feedback for this blog post was incredible, and I’m not joking when I say: I saved many admins weekends. ;) It has shown, that this error still occurs with Exchange 2016 and even 2019. Maybe not because of the same, with Exchange 2013 CU6 fixed bug, but maybe for other reasons.

NetScaler Gateway - Cannot complete your request

A customer reported a weird problem with his NetScaler Gateway. Upon the first load of the website, they got an error “Cannot complete your request”. After clicking OK the error disappeared and does not occured again after reloading the website. Only after closing and re-opening the browser. I got this message in Firefox and Internet Explorer, but not from a remote machine, e.g. my PC at the office. Patrick Terlisten/ vcloudnine.

Out of space - first steps when a datastore runs out of space

This is a situation that never should happen, and I had to deal with it only a couple of times in more than 10y working with VMware vSphere/ ESXi. In most cases, the reason for this was the usage of thin-provisioned disks together with small datastores. Yes, that’s a bad design. Yes, this should never happen. There is a nearly 100% chance that this setup will fail one day. Either because someone dumps much data into the VMs, or because of VM snapshots.

Windows NPS - Authentication failed with error code 16

Today, a customer called me and reported, on the first sight, a pretty weired error: Only Windows clients were unable to login into a WPA2-Enterprise wireless network. The setup itself was pretty simple: Cisco Meraki WiFi access points, a Windows Network Protection Server (NPS) on a Windows Server 2016 Domain Controller, and a Sophos SG 125 was acting as DHCP for different WiFi networks. Windows clients failed to authenticate, but Apple iOS, Android, and even Windows 10 Tablets had no problem.

Client-specific message size limits - or the reason why iOS won't sent emails

Last week, a customer complained that he could not send emails with pictures with the native iOS email app. He attached three, four or five pictures to an emails, pushed the send button and instantly an error was displayed. We checked the different connectors as well as the organizational limit for messages. The test mails were between 10 to 20 MB, and the message size limit was much higher. The cross-check with Outlook Web Access indicated, that the issue was not a configured limit on one of the Exchange connectors.

Veeam and StoreOnce: Wrong FC-HBA driver/ firmware causes Windows BSoD

One of my customers bought a very nice new backup solution, which consists of a HPE StoreOnce 5100 with ~ 144 TB usable capacity, and a new HPE ProLiant DL380 Gen10 with Windows Server 2016 as new backup server. StoreOnce and backup server will be connected with 8 Gb Fibre-Channel and 10 GbE to the existing network and SAN. Veeam Backup & Replication 9.5 U3a is already in use, as well as VMware vSphere 6.

Database Availability Group (DAG) witness is in a failed state

As part of a maintenance job I had to update a 2-node Exchange Database Availability Group and a file-share witness server. After the installation of Windows updates on the witness server and the obligatory reboot, the witness left in a failed state. [PS] C:\Windows\system32>Get-DatabaseAvailabilityGroup -Identity DAG1 -Status | fl *wit* WARNING: Database availability group ‘DAG01’ witness is in a failed state. The database availability group requires the witness server to maintain quorum.

Out-of-Office replies are dropped due to empty MAIL FROM

Today I had an interesting support call. A customer noticed that Out-of-Office replies were not received by recipients, even though the OoO option were enabled for internal and external recipients. Internal recipients got the OoO reply, but none of the external recipients. The Message Tracking Log is a good point to start. I quickly discovered that the Exchange server was unable to send the OoO mails. You can use the eventid FAIL to get a list of all failed messages.

"Cannot execute upgrade script on host" during ESXi 6.5 upgrade

I was onsite at one of my customers to update a small VMware vSphere 6.0 U3 environment to 6.5 U2c. The environment consists of three hosts. Two hosts in a cluster, and a third host is only used to run a HPE StoreVirtual Failover Manager. The update of the first host, using the Update Manager and a HPE custom ESX 6.5 image, was pretty flawless. But the update of the second host failed with “Cannot execute upgrade script on host”

Veeam backups fails because of time differences

Last week I had an interesting incident at a customer. The customer reported that one of multiple Veeam backup jobs jobs constantly failed. The backup job included two VMs, and the backup of one of these VMs failed with this error: Error: Failed to open VDDK disk [[VMDS-SAS-01] VMDC1/VMDC1_1.vmdk] ( is read-only mode - [true] ) Failed to open virtual disk Logon attempt with parameters [VC/ESX: [vcenter.domain.tld];Port: 443;Login: [ADAdministrator];VMX Spec: [moref=vm-59];Snapshot mor: [snapshot-20226];Transports: [san];Read Only: [true]] failed because of the following errors: Failed to open virtual disk Logon attempt with parameters VC/ESX: [vcenter.