Category Archives: Solutions

Tips, fixes, walkarounds.

Guacamole 1.4: “Creation of WebSocket tunnel to guacd failed”

Problem: Guacamole 1.4 shows “internal error” when making any connection and in /var/log/tomcat9/catalina.out you see something like:

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Guacamole 1.4: “Log in failed” for RDP connections

Problem (Guacamole 1.4 while connecting to an RDP server): …and in logs:

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Confluence: broken links and macros after migrating Postgres database

Problem: after migrating Atlassian Confluence PostgreSQL database to another server, you’re seeing lots of broken links (in red color) and some navigation macros not working properly (showing errors such as “page not found”). The first thing Atlassian themselves and their … Continue reading

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Proxmox: QEMU Guest Agent is not running — qmp command ‘guest-ping’ failed

Hey fellow Internet dweller, are you worried about the following message appearing during backup of a suspended virtual machine in Proxmox?

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Apple Pro Display XDR: presets not showing up after firmware update

Problem: Apple Pro Display XDR not showing its built-in presets in System Preferences > Displays and clicking “Customize…” brings up an empty window.

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Apache Guacamole: RDP printer not working, “error parsing HTTP request header”, “Invalid character found” etc

If you’re using Apache Guacamole 1.0.0 behind an nginx reverse proxy, and Guacamole’s RDP printer doesn’t work, and browser console logs error 400, welcome to read further.

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macOS High Sierra: Spotlight search not working — “Database mapping failed” error spammed to the system log

Solution can be found here (read the post that starts from “I’ve solved this…” by Design Complex).

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macOS High Sierra doesn’t start after updating (stuck on Apple logo) — “failed to unwrap volume key” error

The first thing you want to do when your Mac system doesn’t start is to start up into the verbose mode to see if there any error messages. Don’t try to fix the problem before diagnosing!

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Windows Server 2019: RD Session Host — ChangeMode “Invalid operation” exception

If you’re changing the client access licensing mode of your RD Session Host using the PowerShell $obj.ChangeMode(…) command and it fails with an error saying “Exception … Invalid operation”…

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“Install %OS%.app does not appear to be a valid OS installer application” (createinstallmedia error)

If you’re trying to create a bootable installer for an older macOS version (like El Capitan) with createinstallmedia, and it fails with a “does not appear to be a valid OS installer” error, quite possible the actual problem is that … Continue reading

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