https://www.maerklin.de/...ce/downloads/msw-updates

Firmware Update Information 5.4.0.21
First September Update 2025

Published: September 8, 2025 at 03:55 PM

Bug fixes of the release version and improvements. The first update to Version 5 takes about 60 seconds due to internal adjustments!

News

OS
At startup, a message will be displayed if there is an internet connection and a new version is available.

OS
When an update has been found, the update process can now be started directly from the notification dialog.

Core
While checking an update file, a dialog is now displayed to make it clear that the MSW is still working.

Improvements

OS
For the automatically generated password for configuration mode, not all characters are valid anymore to avoid confusion and problems with the 2D code.

Bug Fixes

OS
It is now again no longer possible to execute update files of the Märklin WLAN Box.

Core
Error messages during the update are now displayed correctly again.

Web
Update files of length 0 are now directly rejected.

Web
Corrected an error that caused the serial number in the web app to be displayed incorrectly.