I have an SDL Web 8.5 environment with DXA 1.7 .Net working fine. I have downloaded and compiled (as per docs) DXA 1.7 Java and deployed it to Tomcat. However, I get a Context error, as shown below.
I can confirm the Context Service is registered with the Discovery and it is working fine (.Net web app works).
12:58:27.706 [http-nio-64925-exec-6] ERROR c.s.w.c.i.m.ViewModelRegistryImpl - Cannot determine entity type for semantic schema names: '[http://www.sdl.com/web/schemas/core:PageNavigationMetadata]'. Please make sure that an entry is registered for this view name in the ViewModelRegistry. 12:58:27.710 [http-nio-64925-exec-6] ERROR c.s.w.c.controller.PageController - Exception while processing request for: / java.lang.NullPointerException: null at com.sdl.webapp.common.impl.mapping.SemanticMapperImpl.createInstance(SemanticMapperImpl.java:53) ~[dxa-common-impl-1.7.0.jar:1.7.0] at com.sdl.webapp.common.impl.mapping.SemanticMapperImpl.createEntity(SemanticMapperImpl.java:96) ~[dxa-common-impl-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.PageBuilderImpl.createViewModel(PageBuilderImpl.java:306) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.PageBuilderImpl.createPageModel(PageBuilderImpl.java:274) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.PageBuilderImpl.createPage(PageBuilderImpl.java:194) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.ModelBuilderPipelineImpl.createPageModel(ModelBuilderPipelineImpl.java:53) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.AbstractDefaultContentProvider$1.tryFindPage(AbstractDefaultContentProvider.java:232) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.AbstractDefaultContentProvider$1.tryFindPage(AbstractDefaultContentProvider.java:212) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.common.util.LocalizationUtils.findPageByPath(LocalizationUtils.java:162) ~[dxa-common-api-1.7.0.jar:1.7.0] at com.sdl.webapp.tridion.mapping.AbstractDefaultContentProvider.getPageModel(AbstractDefaultContentProvider.java:212) ~[dxa-tridion-provider-1.7.0.jar:1.7.0] at com.sdl.webapp.common.controller.PageController.getPageModel(PageController.java:296) ~[dxa-common-api-1.7.0.jar:1.7.0] at com.sdl.webapp.common.controller.PageController.handleGetPage(PageController.java:120) ~[dxa-common-api-1.7.0.jar:1.7.0] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_121] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_121] at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_121] at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219) ~[spring-web-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) ~[spring-web-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:100) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:604) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:565) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778) ~[spring-webmvc-3.1.4.RELEASE.jar:3.1.4.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) [servlet-api.jar:na] at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [servlet-api.jar:na] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) [catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [catalina.jar:8.5.11] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-websocket.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [catalina.jar:8.5.11] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) [spring-web-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) [spring-web-3.1.4.RELEASE.jar:3.1.4.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.11] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.11] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [catalina.jar:8.5.11] at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.11] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [catalina.jar:8.5.11] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) [tomcat-coyote.jar:8.5.11] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.11] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798) [tomcat-coyote.jar:8.5.11] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434) [tomcat-coyote.jar:8.5.11] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.11] at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_121] at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_121] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.11] at java.lang.Thread.run(Unknown Source) [na:1.8.0_121]