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I have about 30 layers. Each of them has project CRS EPSG:4326, which requires change to EPSG:3857.

I know how to do it, which also has been explained here:

https://gis.stackexchange.com/questions/73686/changing-projection-of-shapefile-in-qgis|

Unfortunately, I would like to do these steps for my all layers.

I tried to find some way, and the hints below put me on the right track

Change style properties of several layers simultaneously?

where I tried 2 options visible below.

enter image description here

Unfortunately, none of them was working.

Is there any way to at least copy the CRS settings for the layers?

Babel
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Geographos
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2 Answers2

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You can group all layers you want to change, right click the group and then "Set group CRS" should do what you asked for.

sn1ks
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Be aware: you want to reproject your layer or change the CRS of the layer? That are two fundamentally different things and the linked post presents options for both: that could lead to confusion.

Normally, you should not change CRS, but reproject (click the link to see why).

To reproject multiple layers at once, run Menu Processing / Toolbox / Reproject Layer and check the box next to Run as Batch Process… (bottom left). Fill in the dialog window that opens (see screenshot).

If you really want to batch-assign a new layer CRS, use Menu Processing / Toolbox / Assign projection and again run it as batch process.

Projections are not part of the style, that's why you can't use the approach with Copy style.

enter image description here

Edit

By the way: don't confuse layer- and project-CRS, that are complete different things! You write:

...30 layers. Each of them has project CRS EPSG:4326, which requires change to EPSG:3857.

If you want to change the project CRS, simply do that at the bootom right of your QGIS window, no need to change anything for the layers. Make yourself comfortable with the difference of layer- vs. project CRS, see here for details.

So basically, you should differentiate between:

  1. Reproject a layer
  2. Assign (change) a layer CRS
  3. Change project CRS
Babel
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    I just wanted to change the layer CRS without reprojection. Is something like this possible with the batch process? – Geographos Jun 30 '21 at 14:44
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    Run Menu Processing / Toolbox / Assign projection in batch mode, see updated answer. – Babel Jun 30 '21 at 14:46
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    Could you tell me why I shouldn't just change CRS but reproject? – Geographos Jun 30 '21 at 16:20
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    The reason is explained in detail in the link in my answer: change CRS is made for data that comes with no (or wrong) CRS definition. When you "change"/set the CRS of a correctly positioned layer, it will probably be placed in a wrong place on earth. A layer in EPSG:4326, changed to EPSG:3857, will show a point with geographic coordinates 10° E, 45° N (=northern Italy) somewhere in the Atlantic south of Ghana: coordinates are interpreted as 10 meters east of the prime meridian and 45 meters north of the Equator. That's probably not what you want. That's why you should reproject. – Babel Jun 30 '21 at 16:34
  • Don't confuse layer- and project-CRS - see updated answer. After re-reading your question, I'm nor really sure what you want to change and why you want to set a different CRS for your layer. Be aware not to make wrong settings. – Babel Jun 30 '21 at 19:17