I downloaded SQL Developer 4.1.3.20. Before that, I installed JDK 8. I am using a MacBook with El Capitan.
Now, when I start it by clicking on the symbol, it shows a bar with about 10% loaded but never continues to load. Thanks to stackoverflow I found out that I can start the SQL developer from the terminal by calling /Applications/SQLDeveloper.app/Contents/MacOS/sqldeveloper.sh, which works normally.
I found a product.conf under /.sqldeveloper/4.1.0 and changed the path to the JAVA_HOME. Because that did not make sense to me, I also created a folder names 4.1.3 and 4.1.3.20, copied the same file there. Did not make a difference.
I also checked the script itself, and it uses the current path to my Java home with the option "-v 1.8".
I can't see why it works in the terminal but not when I click the symbol.
EDIT
Now it also won't work any more in the terminal. I get the exception:
java.lang.Exception: Stack trace
at java.lang.Thread.dumpStack(Thread.java:1329)
at oracle.ideimpl.MainWindowImpl.<init>(MainWindowImpl.java:166)
at oracle.ide.osgi.Activator.setupWindow(Activator.java:281)
at oracle.ide.osgi.Activator.start(Activator.java:135)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
at java.security.AccessController.doPrivileged(Native Method)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:390)
at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1176)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:559)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:544)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:457)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)
at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.internalStart(EquinoxLauncher.java:271)
at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.start(EquinoxLauncher.java:241)
at org.eclipse.osgi.launch.Equinox.start(Equinox.java:258)
at org.netbeans.core.netigso.Netigso.start(Netigso.java:191)
at org.netbeans.NetigsoHandle.startFramework(NetigsoHandle.java:209)
at org.netbeans.ModuleManager.enable(ModuleManager.java:1352)
at org.netbeans.ModuleManager.enable(ModuleManager.java:1156)
at org.netbeans.core.startup.ModuleList.installNew(ModuleList.java:340)
at org.netbeans.core.startup.ModuleList.trigger(ModuleList.java:276)
at org.netbeans.core.startup.ModuleSystem.restore(ModuleSystem.java:301)
at org.netbeans.core.startup.Main.getModuleSystem(Main.java:181)
at org.netbeans.core.startup.Main.getModuleSystem(Main.java:150)
at org.netbeans.core.startup.Main.start(Main.java:307)
at org.netbeans.core.startup.TopThreadGroup.run(TopThreadGroup.java:123)
at java.lang.Thread.run(Thread.java:745)
I installed an older version (4.1.0) and, surprisingly, it worked.