Solution: Apple Thunderbolt Display brightness control doesn’t work anymore

Apparently, there’s a macOS bug that if your Mac has been connected to a Thunderbolt Display for a long time, the brightness of the display can no longer be adjusted (neither by pressing the according F1/F2 keys on your keyboard nor by using the brightness slider in the display settings of the system preferences).

The simple yet surprising fix is:

  1. Unplug your Thunderbolt Display’s Thunderbolt cable, and plug it in again
  2. The display’s brightness will be adjustable again

 

(credits: https://forums.macrumors.com/threads/thunderbolt-brightness-control-settings-gone.1254406/)

GitLab 10.5 and later: Solution for error “Validation failed for domain” with Let’s Encrypt

GitLab 10.5 introduced built-in support for Let’s Encrypt.

Unfortunately, if you follow the official GitLab instructions how to enable Let’s Encrypt support, you may encounter the following error when rebuilding GitLab:

Running handlers:
There was an error running gitlab-ctl reconfigure:

letsencrypt_certificate[yourhost.yourdomain.com] (letsencrypt::http_authorization line 3) had an error: RuntimeError: acme_certificate[staging] (/opt/gitlab/embedded/cookbooks/cache/cookbooks/letsencrypt/resources/certificate.rb line 20) had an error: RuntimeError: [yourhost.yourdomain.com] Validation failed for domain yourhost.yourdomain.com

Running handlers complete
Chef Client failed. 11 resources updated in 11 seconds

Warnings:

Let’s Encrypt is enabled, but external_url is using http

The last line is rather misleading, as the domain validation can apparently also fail if one sets  external_url = “https://yourhost.yourdomain.com”

As a workaround, add the following two additional lines to /etc/gitlab/gitlab.rb (hat tip to Kai Mindermann and Thomas Jost for the hints):

nginx['redirect_http_to_https_port'] = 80
nginx['redirect_http_to_https'] = true

 

So, all in all, you need to set in /etc/gitlab/gitlab.rb:

external_url 'https://yourhost.yourdomain.com'

and add the following lines (adjust the notification e-mail address):

letsencrypt['enable'] = true
letsencrypt['contact_emails'] = ['gitlab-notifications@yourdomain.com'] # optional
nginx['redirect_http_to_https_port'] = 80
nginx['redirect_http_to_https'] = true

Make sure that your firewall doesn’t block access to ports 22 (SSH), 80 (HTTP), 443 (HTTPS).

After that, reconfigure GitLab (in a shell):

# gitlab-ctl reconfigure

That’s it! You can now register/login at https://yourhost.yourdomain.com.

Solution for: Proxmox backup error due to iothread=1

If you see the following error when trying to backup a KVM VM image on Proxmox:

ERROR: Backup of VM 100 failed – disk ‘scsi0’ ‘zfsvols:vm-100-disk-1’ (iothread=on) can’t use backup feature currently. Please set backup=no for this drive at /usr/share/perl5/PVE/VZDump/QemuServer.pm line 77. INFO: Backup job finished with errors TASK ERROR: job errors

edit /etc/pve/qemu-server/100.conf, look for a line similar to

scsi0: zfsvols:vm-100-disk-1,iothread=1,size=70G

and change it to

scsi0: zfsvols:vm-100-disk-1,iothread=0,size=70G

Afterwards, it’s possible to backup the VM.

Wi-Fi troubles with a B&W Zeppelin Air and AirPort Extreme/AirPort Time Capsule?

Recently, my B&W Zeppelin Air speakers have started to show a weird problem: I managed to stream music via AirPlay to them, but they would only play the music for a few seconds, then stop for a seemingly random amount of time, then play the music for a second or so again, then stop again, and so on. A lengthy stuttering, so to say.

Turns out, the reason for these troubles was that I set the AirPort Time Capsule’s main SSID wireless security to “WPA2 Personal” and the guest SSID’s wireless security to “WPA/WPA2 Personal”. Now I’ve set them both to “WPA/WPA2 Personal” and the Zeppelin Air works great again! Streaming also works fine if both “networks” are set to “WPA2 Personal” (which is a somewhat safer setting than WPA/WPA2 mixed mode, some old Wi-Fi cards might not work anymore, however).

I can’t quite explain this, based on the observed symptoms (one would expect things to either work or not work, but not half-way). It seems the AirPort Extreme/Time Capsule has troubles using different wireless security protocols for the main network and the guest network. This might also partly explain the generally shaky Wi-Fi connectivity I’ve experienced since upgrading my Macs to Yosemite – the random Wi-Fi connectivity drops even kept occurring in 10.10.2. I’ll keep an eye on it.

 

HP 48G: How to fix the “Warning: Invalid Card Data” problem

Recently, my good old HP 48G calculator (one of the best calculators ever built and my longtime personal favourite till today) started displaying the following message whenever I switched it on:

Warning: Invalid Card Data

Which seems a bit odd at first, considering the 48G model has no card slot (only the 48GX model has one). Luckily, there’s a simple solution: Execute the PINIT command by typing “PINIT” (without the double quotes) and pressing the ENTER key.

There’s a great, detailed explanation of this problem and the according fix in the “invalid card data at my hp48g” thread over at the independent HP calculator museum. If this warning message appears on a HP 48GX and the problem persists after applying this fix, take a look at step 3 described in the  article titled “Message, Invalid Card Data, is Displayed when the Calculator is Turned On” on HP’s support forum.

Wouldn’t it be a pity if a company with such a great history and so many great hardware products ceased to be a hardware company?