Error in PostgreSQL/PostGIS Access to offline bands disabled
Have you set the environment variables to enable rasters ?


  As of PostGIS 2.1.3, out-of-db rasters and all raster drivers are disabled by default. In order to re-enable these, you need to set the following environment variables: POSTGIS_GDAL_ENABLED_DRIVERS and POSTGIS_ENABLE_OUTDB_RASTERS in the server environment.
  
  If you want to enable offline raster:
  
  POSTGIS_ENABLE_OUTDB_RASTERS=1
    Any other setting or no setting at all will disable out of db rasters.
  
  In order to enable all GDAL drivers available in your GDAL install, set this environment variable as follows
  
  POSTGIS_GDAL_ENABLED_DRIVERS=ENABLE_ALL


From http://postgis.net/docs/postgis_installation.html#install_short_version