We have a custom search portlet that displays links to the results using URLs generated by AssetRenderer. Here is a sample of the code:

String urlMaximzed = renderer.getURLView((LiferayPortletResponse) actionResponse, WindowState.MAXIMIZED);

String urlviewincontext = renderer.getURLViewInContext((LiferayPortletRequest) actionRequest, LiferayPortletResponse) actionResponse, null);

Printing out these URLs gives:

2021-10-26 18:27:55.739 INFO  [http-nio-8080-exec-4][CustomSearchPortlet:740] searchDocuments: urlMaximized: http://localhost:8080/web/avengers/search?p_p_id=com_liferay_document_library_web_portlet_DLPortlet&p_p_lifecycle=0&p_p_state=maximized&p_p_mode=view&_com_liferay_document_library_web_portlet_DLPortlet_mvcRenderCommandName=%2Fdocument_library%2Fview_file_entry&_com_liferay_document_library_web_portlet_DLPortlet_fileEntryId=35816

2021-10-26 18:27:55.742 INFO  [http-nio-8080-exec-4][CustomSearchPortlet:755] searchDocuments: urlviewincontext = http://localhost:8080/c/document_library/find_file_entry?p_l_id=20&noSuchEntryRedirect=null&fileEntryId=35816

Clicking on the first URL (maximized) in the portlet seems to work fine for all asset types. Clicking on the second (view in context) works for assets other than documents. For documents, clicking on the link produces an error with the following stack trace:

2021-10-26 17:32:29.694 WARN  [http-nio-8080-exec-1][PortalImpl:6884] java.lang.NullPointerException
java.lang.NullPointerException
    at com.liferay.portal.kernel.portlet.PortletIdCodec.decodePortletName(PortletIdCodec.java:48)
    at com.liferay.portal.service.impl.PortletLocalServiceImpl.fetchPortletById(PortletLocalServiceImpl.java:405)
    at com.liferay.portal.service.impl.PortletLocalServiceImpl.getPortletById(PortletLocalServiceImpl.java:523)
    at sun.reflect.GeneratedMethodAccessor193.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.liferay.portal.spring.aop.AopMethodInvocationImpl.proceed(AopMethodInvocationImpl.java:50)
    at com.liferay.portal.spring.aop.AopInvocationHandler.invoke(AopInvocationHandler.java:49)
    at com.sun.proxy.$Proxy44.getPortletById(Unknown Source)
    at com.liferay.portal.kernel.service.PortletLocalServiceUtil.getPortletById(PortletLocalServiceUtil.java:339)
    at com.liferay.portlet.internal.PortletURLFactoryImpl.create(PortletURLFactoryImpl.java:81)
    at com.liferay.portal.kernel.portlet.PortletURLFactoryUtil.create(PortletURLFactoryUtil.java:59)
    at com.liferay.portal.struts.FindStrutsAction.execute(FindStrutsAction.java:99)
    at com.liferay.portal.struts.ActionAdapter.execute(ActionAdapter.java:40)
    at com.liferay.portal.struts.PortalRequestProcessor._process(PortalRequestProcessor.java:415)
    at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:155)
    at com.liferay.portal.internal.servlet.MainServlet.doGet(MainServlet.java:206)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
    at com.liferay.portal.internal.servlet.MainServlet.service(MainServlet.java:623)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:124)
    at com.liferay.portal.servlet.filters.password.modified.PasswordModifiedFilter.processFilter(PasswordModifiedFilter.java:62)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.servlet.filters.lockout.LockoutFilter.processFilter(LockoutFilter.java:58)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:147)
    at com.liferay.portal.servlet.filters.secure.BaseAuthFilter.processFilter(BaseAuthFilter.java:357)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:147)
    at com.liferay.portal.sharepoint.SharepointFilter.processFilter(SharepointFilter.java:88)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:147)
    at com.liferay.portal.servlet.filters.virtualhost.VirtualHostFilter.processFilter(VirtualHostFilter.java:270)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:147)
    at com.liferay.portal.monitoring.internal.servlet.filter.MonitoringFilter.processFilter(MonitoringFilter.java:183)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:196)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:99)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:196)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:99)
    at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176)
    at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
    at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
    at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:389)
    at com.liferay.portal.servlet.filters.urlrewrite.UrlRewriteFilter.processFilter(UrlRewriteFilter.java:65)
    at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:49)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:215)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:175)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:99)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:175)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:99)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:196)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:99)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:104)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:880)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1601)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)
2021-10-26 17:32:30.016 ERROR [http-nio-8080-exec-1][status_jsp:854] null

All of this worked correctly in 6.x, we're just seeing it now as we're migrating to 7.2.

For brevity, AssetRenderer.getURLView returns a URL that works correctly. So does AssetRenderer.getURLExport. Only AssetRenderer.getURLViewInContext is returning a bad URL.