diff --git a/bundles/org.eclipse.osgi.tests/.classpath b/bundles/org.eclipse.osgi.tests/.classpath
index 71ce997..2650588 100644
--- a/bundles/org.eclipse.osgi.tests/.classpath
+++ b/bundles/org.eclipse.osgi.tests/.classpath
@@ -124,6 +124,7 @@
 	<classpathentry kind="src" output="bundle_tests/test.bug449484" path="bundles_src/test.bug449484"/>
 	<classpathentry kind="src" output="bundle_tests/wrapper.hooks.a" path="bundles_src/wrapper.hooks.a"/>
 	<classpathentry kind="src" output="bundle_tests/test.protocol.handler" path="bundles_src/test.protocol.handler"/>
+	<classpathentry kind="src" output="bundle_tests/test.protocol.handler.user" path="bundles_src/test.protocol.handler.user"/>
 	<classpathentry kind="src" output="bundle_tests/test.bug471551" path="bundles_src/test.bug471551"/>
 	<classpathentry kind="src" output="bundle_tests/test.dynamicimport" path="bundles_src/test.dynamicimport"/>
 	<classpathentry kind="src" output="bundle_tests/test.bug490902.a" path="bundles_src/test.bug490902.a"/>
diff --git a/bundles/org.eclipse.osgi.tests/build.properties b/bundles/org.eclipse.osgi.tests/build.properties
index ad43e4e..b5f9ec7 100644
--- a/bundles/org.eclipse.osgi.tests/build.properties
+++ b/bundles/org.eclipse.osgi.tests/build.properties
@@ -263,6 +263,8 @@
 manifest.bundle_tests/wrapper.hooks.a.jar = META-INF/MANIFEST.MF
 source.bundle_tests/test.protocol.handler.jar = bundles_src/test.protocol.handler/
 manifest.bundle_tests/test.protocol.handler.jar = META-INF/MANIFEST.MF
+source.bundle_tests/test.protocol.handler.user.jar = bundles_src/test.protocol.handler.user/
+manifest.bundle_tests/test.protocol.handler.user.jar = META-INF/MANIFEST.MF
 source.bundle_tests/test.bug471551.jar = bundles_src/test.bug471551/
 manifest.bundle_tests/test.bug471551.jar = META-INF/MANIFEST.MF
 source.bundle_tests/test.dynamicimport.jar = bundles_src/test.dynamicimport/
@@ -403,6 +405,7 @@
                      bundle_tests/test.bug449484.jar,\
                      bundle_tests/wrapper.hooks.a.jar,\
                      bundle_tests/test.protocol.handler.jar,\
+                     bundle_tests/test.protocol.handler.user.jar,\
                      bundle_tests/test.bug471551.jar,\
                      bundle_tests/test.dynamicimport.jar,\
                      bundle_tests/test.bug490902.b.jar,\
diff --git a/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/META-INF/MANIFEST.MF b/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/META-INF/MANIFEST.MF
new file mode 100644
index 0000000..2e05daf
--- /dev/null
+++ b/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/META-INF/MANIFEST.MF
@@ -0,0 +1,5 @@
+Manifest-Version: 1.0
+Bundle-ManifestVersion: 2
+Bundle-SymbolicName: test.protocol.handler.user
+Bundle-Activator: test.protocol.handler.user.Activator
+Import-Package: org.osgi.framework
diff --git a/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/test/protocol/handler/user/Activator.java b/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/test/protocol/handler/user/Activator.java
new file mode 100644
index 0000000..fef905e
--- /dev/null
+++ b/bundles/org.eclipse.osgi.tests/bundles_src/test.protocol.handler.user/test/protocol/handler/user/Activator.java
@@ -0,0 +1,21 @@
+package test.protocol.handler.user;
+
+import java.net.URL;
+import org.osgi.framework.BundleActivator;
+import org.osgi.framework.BundleContext;
+
+public class Activator implements BundleActivator {
+
+	@Override
+	public void start(BundleContext context) throws Exception {
+		URL testURL = new URL("testing1://test");
+		testURL.openConnection();
+		System.out.println(testURL);
+	}
+
+	@Override
+	public void stop(BundleContext context) throws Exception {
+		// nothing
+	}
+
+}
diff --git a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AbstractFrameworkHookTests.java b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AbstractFrameworkHookTests.java
index cdbaa3f..f7726f3 100644
--- a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AbstractFrameworkHookTests.java
+++ b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AbstractFrameworkHookTests.java
@@ -14,6 +14,9 @@
 package org.eclipse.osgi.tests.hooks.framework;
 
 import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.Enumeration;
@@ -31,8 +34,11 @@
 
 public abstract class AbstractFrameworkHookTests extends CoreTest {
 	protected static class BasicURLClassLoader extends URLClassLoader {
-		public BasicURLClassLoader(URL[] urls, ClassLoader parent) {
+		private volatile String testURL;
+
+		public BasicURLClassLoader(URL[] urls, ClassLoader parent, String testURL) {
 			super(urls, parent);
+			this.testURL = testURL;
 		}
 
 		@Override
@@ -56,6 +62,16 @@
 
 		@Override
 		protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+			if (testURL != null) {
+				try {
+					URL fileUrl = new URI(testURL).toURL();
+					fileUrl.toString();
+				} catch (MalformedURLException | URISyntaxException e) {
+					// stop doing the URI creating
+					testURL = null;
+					throw new RuntimeException(e);
+				}
+			}
 			if (name.startsWith("org.eclipse") || name.startsWith("org.osgi.framework.FrameworkUtil")) {
 				Class<?> result = findLoadedClass(name);
 				if (result == null)
@@ -73,6 +89,7 @@
 	protected static final String BUNDLES_ROOT = "bundle_tests";
 
 	protected BasicURLClassLoader classLoader;
+	protected String testURL = null;
 	protected BundleInstaller bundleInstaller;
 
 	public BundleContext getContext() {
@@ -154,6 +171,6 @@
 			urls = new URL[] {new URL(osgiFramework), new URL(osgiFramework + "bin/")};
 		else
 			urls = new URL[] {new URL(osgiFramework)};
-		classLoader = new BasicURLClassLoader(urls, getClass().getClassLoader());
+		classLoader = new BasicURLClassLoader(urls, getClass().getClassLoader(), testURL);
 	}
 }
diff --git a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AllFrameworkHookTests.java b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AllFrameworkHookTests.java
index 53880a5..d86f3ef 100644
--- a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AllFrameworkHookTests.java
+++ b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/AllFrameworkHookTests.java
@@ -24,6 +24,7 @@
 		suite.addTest(new TestSuite(BundleFileWrapperFactoryHookTests.class));
 		suite.addTest(new TestSuite(ContextFinderTests.class));
 		suite.addTest(new TestSuite(DevClassPathWithExtensionTests.class));
+		suite.addTest(new TestSuite(EmbeddedEquinoxWithURLInClassLoadTests.class));
 		return suite;
 	}
 }
diff --git a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/EmbeddedEquinoxWithURLInClassLoadTests.java b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/EmbeddedEquinoxWithURLInClassLoadTests.java
new file mode 100644
index 0000000..c7c1c8c
--- /dev/null
+++ b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/EmbeddedEquinoxWithURLInClassLoadTests.java
@@ -0,0 +1,68 @@
+/*******************************************************************************
+ * Copyright (c) 2013, 2018 IBM Corporation and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.osgi.tests.hooks.framework;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.Map;
+import org.eclipse.osgi.tests.OSGiTestsActivator;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.Constants;
+import org.osgi.framework.launch.Framework;
+
+public class EmbeddedEquinoxWithURLInClassLoadTests extends AbstractFrameworkHookTests {
+
+	private Framework framework;
+
+	@Override
+	protected void setUp() throws Exception {
+		URL myManifest = getClass().getResource("/META-INF/MANIFEST.MF");
+		testURL = myManifest.toExternalForm();
+		super.setUp();
+		File file = OSGiTestsActivator.getContext().getDataFile(getName());
+		Map<String, String> configuration = new HashMap<String, String>();
+		configuration.put(Constants.FRAMEWORK_STORAGE, file.getAbsolutePath());
+		framework = createFramework(configuration);
+	}
+
+	@Override
+	protected void tearDown() throws Exception {
+		stopQuietly(framework);
+		super.tearDown();
+	}
+
+	private void initAndStartFramework() throws Exception {
+		initAndStart(framework);
+	}
+
+	public void testFrameworkClassLoaderWithNewURI() throws Exception {
+		initAndStartFramework();
+	}
+
+	public void testEmbeddedURLHandler() throws Exception {
+		initAndStart(framework);
+		Bundle testHandler = framework.getBundleContext().installBundle(bundleInstaller.getBundleLocation("test.protocol.handler"));
+		testHandler.start();
+		Bundle testHandlerUser = framework.getBundleContext().installBundle(bundleInstaller.getBundleLocation("test.protocol.handler.user"));
+		testHandlerUser.start();
+		try {
+			URL testingURL = new URL("testing1://test");
+			fail("Should not find testing1 protocol: " + testingURL);
+		} catch (MalformedURLException e) {
+			// expected
+		}
+	}
+}
diff --git a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/url/MultiplexingFactory.java b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/url/MultiplexingFactory.java
index 0d4e0b2..5d9ced4 100644
--- a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/url/MultiplexingFactory.java
+++ b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/url/MultiplexingFactory.java
@@ -11,14 +11,24 @@
  *******************************************************************************/
 package org.eclipse.osgi.internal.url;
 
-import java.lang.reflect.*;
+import java.lang.reflect.AccessibleObject;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
 import java.net.URL;
-import java.util.*;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
 import org.eclipse.osgi.framework.log.FrameworkLogEntry;
 import org.eclipse.osgi.internal.framework.EquinoxBundle;
 import org.eclipse.osgi.internal.framework.EquinoxContainer;
 import org.eclipse.osgi.storage.StorageUtil;
-import org.osgi.framework.*;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.FrameworkUtil;
 
 /*
  * An abstract class for handler factory impls (Stream and Content) that can 
@@ -40,6 +50,7 @@
 	 * it the ability to call setAccessible(true) on other types from the java.base module
 	 */
 	static final Collection<AccessibleObject> setAccessible;
+	static final Collection<ClassLoader> systemLoaders;
 	static {
 		Collection<AccessibleObject> result = null;
 		try {
@@ -64,6 +75,18 @@
 			// ingore as if there is no Unsafe
 		}
 		setAccessible = result;
+
+		Collection<ClassLoader> loaders = new ArrayList<>();
+		try {
+			ClassLoader cl = ClassLoader.getSystemClassLoader();
+			while (cl != null) {
+				loaders.add(cl);
+				cl = cl.getParent();
+			}
+		} catch (Throwable t) {
+			// ignore as if no loaders
+		}
+		systemLoaders = Collections.unmodifiableCollection(loaders);
 	}
 	protected EquinoxContainer container;
 	protected BundleContext context;
@@ -101,7 +124,8 @@
 			setParentFactory.invoke(factory, new Object[] {getParentFactory()});
 		} catch (Exception e) {
 			container.getLogServices().log(MultiplexingFactory.class.getName(), FrameworkLogEntry.ERROR, "register", e); //$NON-NLS-1$
-			throw new RuntimeException(e.getMessage(), e);
+			// just return and not have it registered
+			return;
 		}
 		addFactory(factory);
 	}
@@ -116,7 +140,7 @@
 			closeTracker.invoke(factory, (Object[]) null);
 		} catch (Exception e) {
 			container.getLogServices().log(MultiplexingFactory.class.getName(), FrameworkLogEntry.ERROR, "unregister", e); //$NON-NLS-1$
-			throw new RuntimeException(e.getMessage(), e);
+			// just return without blowing up here
 		}
 	}
 
@@ -155,7 +179,7 @@
 		List<Object> current = getFactories();
 		Class<?>[] classStack = internalSecurityManager.getClassContext();
 		for (Class<?> clazz : classStack) {
-			if (clazz == InternalSecurityManager.class || clazz == MultiplexingFactory.class || ignoredClasses.contains(clazz))
+			if (clazz == InternalSecurityManager.class || clazz == MultiplexingFactory.class || ignoredClasses.contains(clazz) || isSystemClass(clazz))
 				continue;
 			if (hasAuthority(clazz))
 				return this;
@@ -169,7 +193,7 @@
 					}
 				} catch (Exception e) {
 					container.getLogServices().log(MultiplexingFactory.class.getName(), FrameworkLogEntry.ERROR, "findAuthorizedURLStreamHandler-loop", e); //$NON-NLS-1$
-					throw new RuntimeException(e.getMessage(), e);
+					// we continue to the next factory here instead of failing
 				}
 			}
 		}
@@ -179,6 +203,17 @@
 		return this;
 	}
 
+	private boolean isSystemClass(final Class<?> clazz) {
+		// we want to ignore classes from the system
+		ClassLoader cl = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
+			@Override
+			public ClassLoader run() {
+				return clazz.getClassLoader();
+			}
+		});
+		return cl == null || systemLoaders.contains(cl);
+	}
+
 	public boolean hasAuthority(Class<?> clazz) {
 		Bundle b = FrameworkUtil.getBundle(clazz);
 		if (!(b instanceof EquinoxBundle)) {