Weblogic: JAR entry META-INF/adfm.xml not found in _wl_cls_gen.jar

You've just deployed your favorite EAR in a WebLogic successfully, but when you open it, an unfriendly HTTP 500 greets you. This usually happens in development mode.

Error 500--Internal Server Error

oracle.jbo.JboException: JBO-29114 ADFContext is not setup to process messages for this exception. Use the exception stack trace and error code to investigate the root cause of this exception. Root cause error code is JBO-29000. Error message parameters are {0=java.io.FileNotFoundException, 1=JAR entry META-INF/adfm.xml not found in C:\Users\yolo\AppData\Roaming\JDeveloper\system12.2.1.2.42.170105.1224\DefaultDomain\servers\DefaultServer\tmp\_WL_user\OalCdqWorkbench\dfoxis\war\WEB-INF\lib\_wl_cls_gen.jar}
 at oracle.jbo.uicli.mom.CpxUtils.getCpxListFromMetadata(CpxUtils.java:512)
 at oracle.jbo.uicli.mom.JUMetaObjectManager.loadCpx(JUMetaObjectManager.java:915)
 at oracle.adf.model.BindingContext.initialize(BindingContext.java:469)
 at oracle.adf.model.BindingRequestHandler.beginRequest(BindingRequestHandler.java:270)
 at oracle.adf.model.servlet.ADFBindingFilter.doFilter(ADFBindingFilter.java:196)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at oracle.adfinternal.view.faces.webapp.rich.RegistrationFilter.doFilter(RegistrationFilter.java:105)
 at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl$FilterListChain.doFilter(TrinidadFilterImpl.java:529)
 at oracle.adfinternal.view.faces.activedata.AdsFilter.doFilter(AdsFilter.java:60)
 at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl$FilterListChain.doFilter(TrinidadFilterImpl.java:529)
 at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:354)
 at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:232)
 at org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at oracle.adf.library.webapp.LibraryFilter.doFilter(LibraryFilter.java:169)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at oracle.security.jps.ee.http.JpsAbsFilter$1.run(JpsAbsFilter.java:141)
 at java.security.AccessController.doPrivileged(Native Method)
 at oracle.security.jps.util.JpsSubject.doAsPrivileged(JpsSubject.java:315)
 at oracle.security.jps.ee.util.JpsPlatformUtil.runJaasMode(JpsPlatformUtil.java:650)
 at oracle.security.jps.ee.http.JpsAbsFilter.runJaasMode(JpsAbsFilter.java:124)
 at oracle.security.jps.ee.http.JpsAbsFilter.doFilter(JpsAbsFilter.java:232)
 at oracle.security.jps.ee.http.JpsFilter.doFilter(JpsFilter.java:94)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at oracle.dms.servlet.DMSServletFilter.doFilter(DMSServletFilter.java:248)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:32)
 at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:78)
 at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3683)
 at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3649)
 at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:326)
 at weblogic.security.service.SecurityManager.runAsForUserCode(SecurityManager.java:197)
 at weblogic.servlet.provider.WlsSecurityProvider.runAsForUserCode(WlsSecurityProvider.java:203)
 at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:71)
 at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2433)
 at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2281)
 at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2259)
 at weblogic.servlet.internal.ServletRequestImpl.runInternal(ServletRequestImpl.java:1691)
 at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1651)
 at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:270)
 at weblogic.invocation.ComponentInvocationContextManager._runAs(ComponentInvocationContextManager.java:348)
 at weblogic.invocation.ComponentInvocationContextManager.runAs(ComponentInvocationContextManager.java:333)
 at weblogic.work.LivePartitionUtility.doRunWorkUnderContext(LivePartitionUtility.java:54)
 at weblogic.work.PartitionUtility.runWorkUnderContext(PartitionUtility.java:41)
 at weblogic.work.SelfTuningWorkManagerImpl.runWorkUnderContext(SelfTuningWorkManagerImpl.java:640)
 at weblogic.work.ExecuteThread.execute(ExecuteThread.java:406)
 at weblogic.work.ExecuteThread.run(ExecuteThread.java:346)
Caused by: java.io.FileNotFoundException: JAR entry META-INF/adfm.xml not found in C:\Users\yolo\AppData\Roaming\JDeveloper\system12.2.1.2.42.170105.1224\DefaultDomain\servers\DefaultServer\tmp\_WL_user\OalCdqWorkbench\dfoxis\war\WEB-INF\lib\_wl_cls_gen.jar
 at sun.net.www.protocol.jar.JarURLConnection.connect(JarURLConnection.java:142)
 at sun.net.www.protocol.jar.JarURLConnection.getInputStream(JarURLConnection.java:150)
 at java.net.URL.openStream(URL.java:1045)
 at oracle.adf.share.common.rc.util.impl.MetadataRegistryImpl.openStream(MetadataRegistryImpl.java:650)
 at oracle.adf.share.common.rc.util.impl.MetadataRegistryImpl.getDomDocument(MetadataRegistryImpl.java:665)
 at oracle.adf.share.common.rc.util.impl.MetadataRegistryImpl.getRegistryPaths(MetadataRegistryImpl.java:247)
 at oracle.adf.share.common.rc.util.impl.MetadataRegistryImpl.visitRegistryPaths(MetadataRegistryImpl.java:160)
 at oracle.adf.share.common.rc.util.impl.MetadataRegistryImpl.visitRegistryPaths(MetadataRegistryImpl.java:116)
 at oracle.jbo.uicli.mom.CpxUtils.getCpxListFromMetadata(CpxUtils.java:491)
 ... 46 more

What to do: Restart WebLogic.

The issue is handled here: https://support.oracle.com/knowledge/Middleware/2244836_1.html
This is a caching issue, so to permanently fix it, upgrade your JDeveloper.