Frequently Asked Questions

Where is “ERROR 4: Unable to open EPSG support file gcs.csv” coming from and what does it mean?

The full message is “ERROR 4: Unable to open EPSG support file gcs.csv. Try setting the GDAL_DATA environment variable to point to the directory containing EPSG csv files.” The GDAL/OGR library prints this text to your process’s stdout stream when it can not find the gcs.csv data file it needs to interpret spatial reference system information stored with a dataset. If you’ve never seen this before, you can summon this message by setting GDAL_DATA to a bogus value in your shell and running a command like ogrinfo:

$ GDAL_DATA="/path/to/nowhere" ogrinfo example.shp -so example
INFO: Open of 'example.shp'
      using driver 'ESRI Shapefile' successful.

Layer name: example
Geometry: Polygon
Feature Count: 67
Extent: (-113.564247, 37.068981) - (-104.970871, 41.996277)
ERROR 4: Unable to open EPSG support file gcs.csv.  Try setting the GDAL_DATA environment variable to point to the directory containing EPSG csv files.

If you’re using GDAL software installed by a package management system like apt or yum, or Homebrew, or if you’ve built and installed it using configure; make; make install, you don’t need to set the GDAL_DATA environment variable. That software has the right directory path built in. If you see this error, it’s likely a sign that GDAL_DATA is set to a bogus value. Unset GDAL_DATA if it exists and see if that eliminates the error condition and the message.

Important

Activate your conda environments. The GDAL conda package will set GDAL_DATA to the proper value if you activate your conda environment. If you don’t activate your conda enviornment, you are likely to see the error message shown above.

Why can’t rasterio find proj.db?

If you see rasterio.errors.CRSError: The EPSG code is unknown. PROJ: proj_create_from_database: Cannot find proj.db it is because the PROJ library (one of rasterio’s dependencies) cannot find its database of projections and coordinate systems. In some installations the PROJ_LIB environment variable must be set for PROJ to work properly.

Important

Activate your conda environments. The PROJ conda package will set PROJ_LIB to the proper value if you activate your conda environment. If you don’t activate your conda enviornment, you are likely to see the exception shown above.