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I activated the grass 7 plug in, but get the following error:

GRASS intit error: GRASS was not found in 'C:PROGRA~1/QGIS3.4/apps/grass76' (GISBASE), provider ans plugin will not work.

I also cannot make a new map set. I only have to option for open grass tools and grass options.

Under Grass options Default 8s selected and a message says >Currently selected Grass installation is not valid.

How do I fix this?

I have removed everything from my pc and reinstalled QGIS and I cannot get it sorted.

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  • I suggest you upgrade to a more recent version of QGIS, (i.e. 3.16 at least) then it should work out.
    – Micha
    Commented Jan 3, 2022 at 10:16
  • I tried that, but it does not install QGIS with Grass only QGIS desktop
    – Danni
    Commented Jan 5, 2022 at 4:43
  • Are you using the OSGeo4W installer? Have a look at the various install options here
    – Micha
    Commented Jan 5, 2022 at 8:09
  • So I have reinstalled QGIS 3.16.15 and followed the command prompts. I see OSGeo4W on my machine, do I need to run it too? I opened QGIS 3.16 with grass, but now open mapset and create new mapset are greyed out. I also get the following error: GRASS init error : GRASS was not found in 'C:/PROGRA~1/QGIS 3.16/apps/grass/grass78' (GISBASE), provider and plugin will not work.
    – Danni
    Commented Jan 5, 2022 at 8:32
  • Can you run GRASS on its own? i.e. under the OSGeo4W menu there should be a shortcut to GRASS. Does that work?
    – Micha
    Commented Jan 5, 2022 at 9:07

1 Answer 1

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From your comment, it's now more clear what you are trying to do. Here are some online resources that will probably help, if you choose to proceed with GRASS GIS:

  1. First, yes you must create a GRASS database with both LOCATION and MAPSET. It's pretty easy. Please refer to this getting started video, and this wiki page. You need to create the LOCATION using the same coordinate system as your contour lines.
  2. Next to create a DEM from contour lines, you will need to import your contours into GRASS as line vectors. Then, here is a wiki page explaining how to prepare a DEM from contours.
  3. Now to extract from that DEM an elevation profile, follow the procedure here.

The first time this will all seem confusing, but you'll find, I think, that investing some effort to learn is worthwhile.

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  • Thank you. I was trying to use the GIS with GRASS to achieve this so I hope I will be able to get everything to work. If I make a new location and mapset in GRASS, will it then work in QGIS with GRASS? (I made a new location and mapset and used the shapefile to determine the co-ords - GRASS in my QGIS still does not work...Under Grass options it says "Currently selected Grass installation is not valid" - Perhaps you know how I can fix this?)
    – Danni
    Commented Jan 6, 2022 at 7:46
  • The location and mapset that you create is GRASS is NOT used by QGIS. When you run GRASS modules from within the Processing toolbox, it creates a new temporary GRASS location, runs the module, saves the output, then wipes that temp location.
    – Micha
    Commented Jan 6, 2022 at 8:10
  • When you start QGIS (3.16) with the QGIS-GRASS shortcut, you should have access to the GRASS modules from the Toolbox. If this is still not working, then something in the installation did not go right. In my experience, using the OSGeo4W installer got all the bits in place.
    – Micha
    Commented Jan 6, 2022 at 8:12
  • And one more comment: from the QGIS Browser tab, you should have access to the GRASS Location and database that you created when starting with GRASS. So if you run the analysis in GRASS, you will be able to see and access the results from within QGIS using the Browser.
    – Micha
    Commented Jan 6, 2022 at 8:14
  • I have never used GRASS only QGIS so this is all a new learning curve for me. I have installed QGIS a few times and I am not sure why its not installing properly. I saw OSGeo4W has a shortcut after installing QGIS but I am not sure how to use it. (I am originally an ArcGIS user but no longer have access).
    – Danni
    Commented Jan 6, 2022 at 9:06

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