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I am trying to georeference a map using a custom projection I created in QGIS. I get the error Transform failed: "Failed to compute GCP transform: Transform is not solvable" Does anyone have any idea what is happening? I can create layers using the custom projection and no problem.

Here is the custom CRS:

DERIVEDPROJCRS["NewGrid",BASEPROJCRS["NAD83 / UTM zone 11N",BASEGEOGCRS["NAD83",DATUM["North American Datum 1983",ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT["metre",1]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],ID["EPSG",4269]],CONVERSION["UTM zone 11N",METHOD["Transverse Mercator",ID["EPSG",9807]],PARAMETER["Latitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8801]],PARAMETER["Longitude of natural origin",-117,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["Scale factor at natural origin",0.9996,SCALEUNIT["unity",1],ID["EPSG",8805]],PARAMETER["False easting",500000,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",0,LENGTHUNIT["metre",1],ID["EPSG",8807]]]],DERIVINGCONVERSION["Affine",METHOD["Affine parametric transformation",ID["EPSG",9624]],PARAMETER["A0",-589354.7808210109,LENGTHUNIT["metre",1],ID["EPSG",8623]],PARAMETER["A1",3.2622101349044312,SCALEUNIT["coefficient",1],ID["EPSG",8624]],PARAMETER["A2",-0.09032554258992082,SCALEUNIT["coefficient",1],ID["EPSG",8625]],PARAMETER["B0",-14081478.9932015,LENGTHUNIT["metre",1],ID["EPSG",8639]],PARAMETER["B1",0.09032554258992082,SCALEUNIT["coefficient",1],ID["EPSG",8640]],PARAMETER["B2",3.262210134904431,SCALEUNIT["coefficient",1],ID["EPSG",8641]]],CS[Cartesian,2],AXIS["(E)",east,ORDER[1],LENGTHUNIT["metre",1]],AXIS["(N)",north,ORDER[2],LENGTHUNIT["metre",1]]]
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  • I suggest you provide the custom CRS as text.
    – Erik
    Commented Mar 18, 2021 at 19:43
  • I'm not quite sure about your workflow and what exactly you want to do. But you could try to georeference the raster map with a simple basemap in a standrad projection like 3857. Than reproject the georeferenced raster (export it and set the custom CRS).
    – Babel
    Commented Mar 18, 2021 at 20:00
  • Unfortunately, these are very old geology maps with no ground points to use with a base map.
    – Angie
    Commented Mar 18, 2021 at 20:03

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