You see map tiles with the message "These basemap tiles will no longer be available as of October 31, 2023. The site administrator can upgrade to the new map at stamen.com/faq."
The free StamenTerrain map theme is discontinued.
You can select another map theme in the LNM menu "View" or you can use a new map theme for the new StamenTerrain which requires an account right here: https://stadiamaps.com/stamen/onboarding/create-account/
Download the map theme file below and install it in LNM map themes: https://www.littlenavmap.org/downloads/Map Themes/
Installation instructions and more information about map themes: https://www.littlenavmap.org/manuals/littlenavmap/release/latest/en/MAPTHEMES.html https://www.littlenavmap.org/manuals/littlenavmap/release/latest/en/MAPDISPLAY.html#map-themes
You will see a new "Stadia StamenTerrain" map in the LNM map themes list and a new entry "Stadia API Key" in LNM options.
Create an account at "stadiamaps.com" and create an API key. Copy the key and insert it into the "Stadia API Key" in LNM options. Restart LNM and StamenTerrain is back.
Note that this service is free if you do not download more than 200000 map tiles a month. No need to use one of the paid plans and no need to enter credit card information.
After installation if you still see tiles with the message:
Go to LNM main menu Tools -> Files and directories -> Show map cache.
Close LNM and delete the stadiastamenterrain and stamenterrain folders to clear the cache.
Alex