Humh.... I suspect the issue is related to the syntax of the URL. In my test, I used the syntax splitting the domain in one XML element and the path in the second one, like you did with UMaps. 2018-01-05 17:17 GMT+01:00 Etienne Legendre email@example.com: First of all, happy new year and thanks for your answer I retry today but no way :-( In France with both Windows 7 32 bits, Windows 10 32 and/or 64 bits OS, I can have 4UMaps maps and can NOT have OpenTopoMap maps If I run QMapSharck software...
Strange, it works fine for me: viking 1.6, Ubuntu 16.04. Can you retry now, in order to check if it was a temporary issue?
Add OpenTopoMap example
Adding Waymarked Trails layers as example
Add 4UMaps example