No data (vector tile) from WMS to GeoWebCache and error response: 400: All backends (1) failed. Last request: 'http://localhost:8881/geoserver/wms?'.

[vitalus]

I would consider the following behavior to be handled better (or in more flexible way):

If WMS service returns no data (no vector features are in tile's bounds to make a vector tile), it's HTTP response 200 with responseLength = -1 from WMS to GeoWebCache.

In this case a GeoWebCacheException is thrown and GWC returns HTML with an underlying message.

I would like to see the following options to be supported for this scenarios:

• Return HTTP 200 but with no data (no HTML or whatever needed, a message is in log file of GeoServer)
• Return HTTP 400 but with no data (no HTML or whatever needed, a message is in log file of GeoServer)
• Return HTTP XXX but definitely I do not like to expose "http://localhost.8881...." outside... It's internal stuff...
• May be something else.

In the end I am not sure how from HTTP point of view to "represent" such situation (from server to client).

As it's open source, I myself played with a code just to customize response being returned by GWC.. minor improvement.

Any opinions how to make it flexible, probably with some configuration options (for GWC behavior) ?

[vitalus]

May be the problem originates from WMS that sends HTTP 200 with no data in vector tile... What if WMS should response with HTTP 204 and then GWC would handle this properly as well...

[whereispoi]

Hello, I also encountered the same problem. May I ask if you have solved it?
I am using an independent geowebcache to obtain .pbf files (vector tiles) from other geoservers, but due to this problem, I have failed too many times, and I can only retrieve partial data. I have set the layer's metaWidthHeight =[1,1] in geowebcache.xml, but it still hasn't resolved the issue.
However, strangely, I found that if I use the embedded geowebcache within geoserver, there is no interruption.
version geoserver = 2.27.1 geowebcache=1.27.1