Post-processing 'geoexplorer/externals/gxp/src/theme/all.css' failed!
Traceback (most recent call last):
whitenoise.django.MissingFileError: The file 'geoexplorer/externals/gxp/src/theme/img/silk/next_blue.png' could not be found with <whitenoise.django.GzipManifestStaticFilesStorage object at 0x7f9f6019fa50>.
The CSS file 'geoexplorer/externals/gxp/src/theme/all.css' references a file which could not be found:
Please check the URL references in this CSS file, particularly any
relative paths which might be pointing to the wrong location.