GeoServer NetCDF store error

I have a problem with adding a new NetCDF store. I use NetCDF plugin for GeoServer. The error is displayed below:

Message text is like (same problem on a different system):

Could not list layers for this store, an error occurred retrieving them: Failed to create reader from file:coverages/Nstor/nstor-cf.nc and hints Hints: EXECUTOR_SERVICE = java.util.concurrent.ThreadPoolExecutor@6d656d0c[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0] REPOSITORY = org.geoserver.catalog.CatalogRepository@2db8b90e System defaults: COMPARISON_TOLERANCE = 1.0E-8 GRID_COVERAGE_FACTORY = GridCoverageFactory TILE_ENCODING = null FEATURE_FACTORY = org.geotools.feature.LenientFeatureFactoryImpl@54728f47 LENIENT_DATUM_SHIFT = true FORCE_LONGITUDE_FIRST_AXIS_ORDER = true STYLE_FACTORY = StyleFactoryImpl FILTER_FACTORY = FilterFactoryImpl FORCE_AXIS_ORDER_HONORING = http

From the error I can conclude that there is a problem with coordinate system or coordinate order. But at the same time I can open the same file in QGIS. QGIS reads coordinate system correctly (see figure below):

I don’t have enough experience to inspect NetCDF file structure in detail with Python and cannot provide more details about the file structure.

Could someone explain how to correct this error?

GeoServer log:

2020-05-08 10:13:46,461 WARN [io.netcdf] - Unable to connect
org.geotools.data.DataSourceException: Unable to connect
    at org.geotools.coverage.io.netcdf.NetCDFReader.<init>(NetCDFReader.java:161)
    at org.geotools.coverage.io.netcdf.NetCDFFormat.getReader(NetCDFFormat.java:94)
    at org.geoserver.catalog.ResourcePool.getGridCoverageReader(ResourcePool.java:1556)
    at org.geoserver.catalog.ResourcePool.getGridCoverageReader(ResourcePool.java:1502)
    at org.geoserver.catalog.impl.CoverageStoreInfoImpl.getGridCoverageReader(CoverageStoreInfoImpl.java:53)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)

Caused by: org.geotools.data.DataSourceException: java.lang.IllegalArgumentException: Couldn't determine time units from unit string 'day as %Y%m%d.%f'
    at org.geotools.coverage.io.netcdf.NetCDFAccess.<init>(NetCDFAccess.java:139)
    at org.geotools.coverage.io.netcdf.NetCDFDriver.connect(NetCDFDriver.java:92)
    at org.geotools.coverage.io.impl.DefaultFileDriver.process(DefaultFileDriver.java:228)
    at org.geotools.coverage.io.netcdf.NetCDFReader.<init>(NetCDFReader.java:158)
    ... 156 more
Caused by: java.lang.RuntimeException: java.lang.IllegalArgumentException: Couldn't determine time units from unit string 'day as %Y%m%d.%f'
    at org.geotools.imageio.netcdf.NetCDFImageReader.setInput(NetCDFImageReader.java:287)
    at javax.imageio.ImageReader.setInput(ImageReader.java:380)
    at org.geotools.coverage.io.netcdf.NetCDFAccess.<init>(NetCDFAccess.java:128)
    ... 159 more
Caused by: java.lang.IllegalArgumentException: Couldn't determine time units from unit string 'day as %Y%m%d.%f'
    at org.geotools.imageio.netcdf.cv.TimeCoordinateVariable.<init>(TimeCoordinateVariable.java:71)
    at org.geotools.imageio.netcdf.cv.CoordinateVariable.create(CoordinateVariable.java:264)
    at org.geotools.imageio.netcdf.NetCDFGeoreferenceManager.initCoordinates(NetCDFGeoreferenceManager.java:616)
    at org.geotools.imageio.netcdf.NetCDFGeoreferenceManager.<init>(NetCDFGeoreferenceManager.java:575)
    at org.geotools.imageio.netcdf.NetCDFImageReader.init(NetCDFImageReader.java:506)
    at org.geotools.imageio.netcdf.NetCDFImageReader.setInput(NetCDFImageReader.java:285)
    ... 161 more
2020-05-08 10:13:46,471 INFO [geoserver.web] - Getting list of coverages for saved store file:workspaces/geoikp/climate_projections_HZG/hotdays_eur11_rcp85_p10_abschg_2036_2065_i.nc
java.lang.RuntimeException: Could not list layers for this store, an error occurred retrieving them: Failed to create reader from file:workspaces/geoikp/climate_projections_HZG/hotdays_eur11_rcp85_p10_abschg_2036_2065_i.nc and hints Hints:
  EXECUTOR_SERVICE = java.util.concurrent.ThreadPoolExecutor@4b14e299[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
  REPOSITORY       = org.geoserver.catalog.CatalogRepository@1f2746ae                                                                                   
System defaults:
  FILTER_FACTORY                   = FilterFactoryImpl                                      
  FEATURE_FACTORY                  = org.geotools.feature.LenientFeatureFactoryImpl@67ffd911
  FORCE_LONGITUDE_FIRST_AXIS_ORDER = true                                                   
  FORCE_AXIS_ORDER_HONORING        = http                                                   
  STYLE_FACTORY                    = StyleFactoryImpl                                       
  GRID_COVERAGE_FACTORY            = GridCoverageFactory                                    
    TILE_ENCODING                  = null                                                   
  LENIENT_DATUM_SHIFT              = true                                                   
  COMPARISON_TOLERANCE             = 1.0E-8                                                 

    at org.geoserver.web.data.layer.NewLayerPageProvider.getItemsInternal(NewLayerPageProvider.java:170)
    at org.geoserver.web.data.layer.NewLayerPageProvider.getItems(NewLayerPageProvider.java:47)

...

Caused by: java.io.IOException: Failed to create reader from file:workspaces/geoikp/climate_projections_HZG/hotdays_eur11_rcp85_p10_abschg_2036_2065_i.nc and hints Hints:
  EXECUTOR_SERVICE = java.util.concurrent.ThreadPoolExecutor@4b14e299[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
  REPOSITORY       = org.geoserver.catalog.CatalogRepository@1f2746ae                                                                                   
System defaults:
  FILTER_FACTORY                   = FilterFactoryImpl                                      
  FEATURE_FACTORY                  = org.geotools.feature.LenientFeatureFactoryImpl@67ffd911
  FORCE_LONGITUDE_FIRST_AXIS_ORDER = true                                                   
  FORCE_AXIS_ORDER_HONORING        = http                                                   
  STYLE_FACTORY                    = StyleFactoryImpl                                       
  GRID_COVERAGE_FACTORY            = GridCoverageFactory                                    
    TILE_ENCODING                  = null                                                   
  LENIENT_DATUM_SHIFT              = true                                                   
  COMPARISON_TOLERANCE             = 1.0E-8                                                 

    at org.geoserver.catalog.ResourcePool.getGridCoverageReader(ResourcePool.java:1558)
    at org.geoserver.catalog.ResourcePool.getGridCoverageReader(ResourcePool.java:1502)
    at org.geoserver.catalog.impl.CoverageStoreInfoImpl.getGridCoverageReader(CoverageStoreInfoImpl.java:53)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.geoserver.catalog.impl.ModificationProxy.invoke(ModificationProxy.java:127)
    at com.sun.proxy.$Proxy28.getGridCoverageReader(Unknown Source)
    at org.geoserver.web.data.layer.NewLayerPageProvider.getItemsInternal(NewLayerPageProvider.java:86)
    ... 145 more

Couldn't determine time units from unit string 'day as %Y%m%d.%f'