A GetCapabilities Web Map Service (WMS) request with ArcGIS for Server 10.3 on a non-English (Czech, German, etc) Windows machine intermittently replaces the decimals of the bounding box with commas. The commas then remain in the bounding box values as the separator until the service is restarted.
Use an external WMS capabilities file:<a href="http://server.arcgis.com/en/server/latest/publish-services/windows/using-external-capabilities-files-with-wms-services.htm" target="_blank">http://server.arcgis.com/en/server/latest/publish-services/windows/using-external-capabilities-files-with-wms-services.htm</a>