Opening a QLR file with double click fails

[christophfriedrich]

What is the bug or the crash?

I was supplied with a .qgs file by a colleague (@m-mohr) that opened in QGIS perfectly fine. I exported its layer as a .qlr file and saved it to disk. Double-clicking on this file to open it in QGIS fails with the message "Invalid data source: <path> is not a valid data source or is not recognized." (This may not be the exact translation, the German original I see on my screen is: "Ungültige Datenquelle: <path> ist keine gültige Datenquelle oder wird nicht erkannt.")

Steps to reproduce the issue

0. Download the attached .txt file and rename the extension to .qgs (I had to rename it due to Github only accepting certain file types)
1. Double-click the .qgs file to open it in QGIS
2. In the Layers panel you see one layer, named "openEO"
3. Right-click on the layer name.
4. Select "Export" -> "Save as layer definition file"
5. Save the file
6. Find the file in your explorer
7. Double-click it
8. QGIS opens, but shows the error stated above

my-test.txt

Please note that the data described in the file will expire at some point.

Versions

<style type="text/css"> p, li { white-space: pre-wrap; } </style>

QGIS-Version	3.20.3-Odense	QGIS-Codeversion	495fbae
Qt-Version	5.12.8
Python-Version	3.8.10
GDAL-Version	3.0.4
PROJ-Version	6.3.1
EPSG-Registraturdatenbankversion	v9.8.6 (2020-01-22)
Kompiliert mit GEOS	3.8.0-CAPI-1.13.1	Läuft mit GEOS	3.8.0-CAPI-1.13.1
Kompiliert mit SQLite	3.31.1	Läuft mit SQLite	3.35.4
PDAL-Versio	2.0.1
PostgreSQL-Client-Version	12.8 (Ubuntu 12.8-0ubuntu0.20.04.1)
SpatiaLite-Version	4.3.0a
QWT-Version	6.1.4
QScintilla2-Version	2.11.2
BS-Version	Ubuntu 20.04.3 LTS
Aktive Python-Erweiterungen	processingdb_managerMetaSearch

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

This is the very first thing I tried with my installation, which I downloaded only minutes earlier following this guide, so it's about as fresh as it gets.

[m-mohr]

On my Windows 10 installation, I can't even double-click the QLR file. It seems it is somehow registered with QGIS (file type is "QGIS Layer Definition" and it shows a QLR icon from QGIS), but double-clicking it gives me the Windows popup, which allows selecting a program to open the file with.

So two issues here:

• I can't find a place where to make this connection during install or in settings, but QLR files should probably be opened in QGIS by default. (It works with QGS files!)
• After selecting QGIS from the file system, I get the same error as @christophfriedrich.

[gioman]

Confirmed. Works fine from QGIS "add layer" menu or Browser.