Thank you. We have upgraded and now it works. For clarity any REST API call would not work before the upgrade.

I just started experimenting with the ProGet REST API. When I make even the simplest request I get a (404 ) Not Found. For example http://<<proget URL>>/health . Is there some sort of service that needs to be installed or turned on? We are using ProGet 5.1.23.21.

My maven ProGet feed has a connector to https://repo1.maven.org/maven2. When a maven command includes "help:effective-pom" I get a NoPluginFoundForPrefixException exception. When I turn on debugging it appears that maven cannot find org.apache.maven.plugins/maven-metadata.xml. If I try the same command without using my ProGet feed(i.e. https://repo1.maven.org/maven2 directly) it succeeds.

Here is the complete debugging output:

mvn help:effective-pom -X
Apache Maven 3.6.2 (40f52333136460af0dc0d7232c0dc0bcf0d9e117; 2019-08-27T11:06:16-04:00)
Maven home: C:\apache-maven-3.6.2\bin\..
Java version: 1.8.0_221, vendor: Oracle Corporation, runtime: C:\Program Files (x86)\Java\jdk1.8.0_221\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "x86", family: "windows"
[DEBUG] Created new class realm maven.api
[DEBUG] Importing foreign packages into class realm maven.api
[DEBUG]   Imported: javax.annotation.* < plexus.core
[DEBUG]   Imported: javax.annotation.security.* < plexus.core
[DEBUG]   Imported: javax.enterprise.inject.* < plexus.core
[DEBUG]   Imported: javax.enterprise.util.* < plexus.core
[DEBUG]   Imported: javax.inject.* < plexus.core
[DEBUG]   Imported: org.apache.maven.* < plexus.core
[DEBUG]   Imported: org.apache.maven.artifact < plexus.core
[DEBUG]   Imported: org.apache.maven.classrealm < plexus.core
[DEBUG]   Imported: org.apache.maven.cli < plexus.core
[DEBUG]   Imported: org.apache.maven.configuration < plexus.core
[DEBUG]   Imported: org.apache.maven.exception < plexus.core
[DEBUG]   Imported: org.apache.maven.execution < plexus.core
[DEBUG]   Imported: org.apache.maven.execution.scope < plexus.core
[DEBUG]   Imported: org.apache.maven.lifecycle < plexus.core
[DEBUG]   Imported: org.apache.maven.model < plexus.core
[DEBUG]   Imported: org.apache.maven.monitor < plexus.core
[DEBUG]   Imported: org.apache.maven.plugin < plexus.core
[DEBUG]   Imported: org.apache.maven.profiles < plexus.core
[DEBUG]   Imported: org.apache.maven.project < plexus.core
[DEBUG]   Imported: org.apache.maven.reporting < plexus.core
[DEBUG]   Imported: org.apache.maven.repository < plexus.core
[DEBUG]   Imported: org.apache.maven.rtinfo < plexus.core
[DEBUG]   Imported: org.apache.maven.settings < plexus.core
[DEBUG]   Imported: org.apache.maven.toolchain < plexus.core
[DEBUG]   Imported: org.apache.maven.usability < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.* < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.authentication < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.authorization < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.events < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.observers < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.proxy < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.repository < plexus.core
[DEBUG]   Imported: org.apache.maven.wagon.resource < plexus.core
[DEBUG]   Imported: org.codehaus.classworlds < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.* < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.classworlds < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.component < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.configuration < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.container < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.context < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.lifecycle < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.logging < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.personality < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.util.xml.Xpp3Dom < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.util.xml.pull.XmlPullParser < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.util.xml.pull.XmlPullParserException < plexus.core
[DEBUG]   Imported: org.codehaus.plexus.util.xml.pull.XmlSerializer < plexus.core
[DEBUG]   Imported: org.eclipse.aether.* < plexus.core
[DEBUG]   Imported: org.eclipse.aether.artifact < plexus.core
[DEBUG]   Imported: org.eclipse.aether.collection < plexus.core
[DEBUG]   Imported: org.eclipse.aether.deployment < plexus.core
[DEBUG]   Imported: org.eclipse.aether.graph < plexus.core
[DEBUG]   Imported: org.eclipse.aether.impl < plexus.core
[DEBUG]   Imported: org.eclipse.aether.installation < plexus.core
[DEBUG]   Imported: org.eclipse.aether.internal.impl < plexus.core
[DEBUG]   Imported: org.eclipse.aether.metadata < plexus.core
[DEBUG]   Imported: org.eclipse.aether.repository < plexus.core
[DEBUG]   Imported: org.eclipse.aether.resolution < plexus.core
[DEBUG]   Imported: org.eclipse.aether.spi < plexus.core
[DEBUG]   Imported: org.eclipse.aether.transfer < plexus.core
[DEBUG]   Imported: org.eclipse.aether.version < plexus.core
[DEBUG]   Imported: org.fusesource.jansi.* < plexus.core
[DEBUG]   Imported: org.slf4j.* < plexus.core
[DEBUG]   Imported: org.slf4j.event.* < plexus.core
[DEBUG]   Imported: org.slf4j.helpers.* < plexus.core
[DEBUG]   Imported: org.slf4j.spi.* < plexus.core
[DEBUG] Populating class realm maven.api
[INFO] Error stacktraces are turned on.
[DEBUG] Message scheme: color
[DEBUG] Message styles: debug info warning error success failure strong mojo project
[DEBUG] Reading global settings from C:\apache-maven-3.6.2\bin\..\conf\settings.xml
[DEBUG] Reading user settings from C:\Users\berubec\.m2\settings.xml
[DEBUG] Reading global toolchains from C:\apache-maven-3.6.2\bin\..\conf\toolchains.xml
[DEBUG] Reading user toolchains from C:\Users\berubec\.m2\toolchains.xml
[DEBUG] Using local repository at C:\Users\berubec\.m2\repository
[DEBUG] Using manager EnhancedLocalRepositoryManager with priority 10.0 for C:\Users\berubec\.m2\repository
[INFO] Scanning for projects...
[DEBUG] Using mirror proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/) for central (https://repo.maven.apache.org/maven2).
[DEBUG] Extension realms for project helloworld:helloworld:war:1.0-SNAPSHOT: (none)
[DEBUG] Looking up lifecycle mappings for packaging war from ClassRealm[plexus.core, parent: null]
[DEBUG] Resolving plugin prefix help from [org.apache.maven.plugins, org.codehaus.mojo]
[DEBUG] Using mirror proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/) for apache.snapshots (http://repository.apache.org/snapshots).
[DEBUG] Using mirror proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/) for apache.snapshots (http://people.apache.org/repo/m2-snapshot-repository).
[DEBUG] Using mirror proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/) for codehaus.org (http://snapshots.repository.codehaus.org).
[DEBUG] Could not find metadata org.apache.maven.plugins/maven-metadata.xml in local (C:\Users\berubec\.m2\repository)
[DEBUG] Failure to find org.apache.maven.plugins/maven-metadata.xml in https://proget.seicdevops.com/maven2/Maven-Enterprise/ was cached in the local repository, resolution will not be reattempted until the update interval of proget has elapsed or updates are forced
[DEBUG] Could not find metadata org.codehaus.mojo/maven-metadata.xml in local (C:\Users\berubec\.m2\repository)
[DEBUG] Failure to find org.codehaus.mojo/maven-metadata.xml in https://proget.seicdevops.com/maven2/Maven-Enterprise/ was cached in the local repository, resolution will not be reattempted until the update interval of proget has elapsed or updates are forced
[DEBUG] Could not find metadata org.apache.maven.plugins/maven-metadata.xml in local (C:\Users\berubec\.m2\repository)
[DEBUG] Could not find metadata org.codehaus.mojo/maven-metadata.xml in local (C:\Users\berubec\.m2\repository)
[DEBUG] Using transporter WagonTransporter with priority -1.0 for https://proget.seicdevops.com/maven2/Maven-Enterprise/
[DEBUG] Using transporter WagonTransporter with priority -1.0 for https://proget.seicdevops.com/maven2/Maven-Enterprise/
[DEBUG] Using connector BasicRepositoryConnector with priority 0.0 for https://proget.seicdevops.com/maven2/Maven-Enterprise/ with username=chris.berube@seicdevops.com, password=***
[DEBUG] Using connector BasicRepositoryConnector with priority 0.0 for https://proget.seicdevops.com/maven2/Maven-Enterprise/ with username=chris.berube@seicdevops.com, password=***
Downloading from proget: https://proget.seicdevops.com/maven2/Maven-Enterprise/org/apache/maven/plugins/maven-metadata.xml
Downloading from proget: https://proget.seicdevops.com/maven2/Maven-Enterprise/org/codehaus/mojo/maven-metadata.xml
[DEBUG] Writing tracking file C:\Users\berubec\.m2\repository\org\apache\maven\plugins\resolver-status.properties
[DEBUG] Writing tracking file C:\Users\berubec\.m2\repository\org\codehaus\mojo\resolver-status.properties
[DEBUG] Could not find metadata org.apache.maven.plugins/maven-metadata.xml in proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/)
[DEBUG] Could not find metadata org.codehaus.mojo/maven-metadata.xml in proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.830 s
[INFO] Finished at: 2019-10-16T14:59:45-04:00
[INFO] ------------------------------------------------------------------------
[ERROR] No plugin found for prefix 'help' in the current project and in the plugin groups [org.apache.maven.plugins, org.codehaus.mojo] available from the repositories [local (C:\Users\berubec\.m2\repository), proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/)] -> [Help 1]
org.apache.maven.plugin.prefix.NoPluginFoundForPrefixException: No plugin found for prefix 'help' in the current project and in the plugin groups [org.apache.maven.plugins, org.codehaus.mojo] available from the repositories [local (C:\Users\berubec\.m2\repository), proget (https://proget.seicdevops.com/maven2/Maven-Enterprise/)]
    at org.apache.maven.plugin.prefix.internal.DefaultPluginPrefixResolver.resolve (DefaultPluginPrefixResolver.java:95)
    at org.apache.maven.lifecycle.internal.MojoDescriptorCreator.findPluginForPrefix (MojoDescriptorCreator.java:266)
    at org.apache.maven.lifecycle.internal.MojoDescriptorCreator.getMojoDescriptor (MojoDescriptorCreator.java:220)
    at org.apache.maven.lifecycle.internal.DefaultLifecycleTaskSegmentCalculator.calculateTaskSegments (DefaultLifecycleTaskSegmentCalculator.java:104)
    at org.apache.maven.lifecycle.internal.DefaultLifecycleTaskSegmentCalculator.calculateTaskSegments (DefaultLifecycleTaskSegmentCalculator.java:83)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:89)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR]
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoPluginFoundForPrefixException