Why does checkout fail generating a Java exception with WebTop/WDK ?

When performing a checkout/edit operation in WebTop/ WDK you may receive a java exception similar to the following :

com.documentum.web.contentxfer.applet.registry.RegKeyException:
Registry Error: com.ms.lang.RegKeyException: open error
com.ms.lang.RegKeyException: open error at
com/ms/lang/RegKey.pRegOpenKey (RegKey.java) at com/ms/lang/RegKey.(RegKey.java) at
com/documentum/web/contentxfer/applet/registry/RegistryWin32. at
com/documentum/web/contentxfer/applet/registry/ClientRegistry.getClientRegistryLocalMachineat
com/documentum/web/contentxfer/applet/ContentXferRegistryHelper.getCheckoutDirectoryat
com/documentum/web/contentxfer/applet/CheckoutApplet.addObjectsToRegistry at
com/documentum/web/contentxfer/applet/EditApplet.executeImplat
com/documentum/web/contentxfer/applet/MicrosoftExecutionMgr.execute at com/documentum/web/contentxfer/applet/SecureApplet.execute at
com/documentum/web/contentxfer/applet/SecureApplet.init at
com/ms/applet/AppletPanel.securedCall0 (AppletPanel.java) at
com/ms/applet/AppletPanel.securedCall (AppletPanel.java) at
com/ms/applet/AppletPanel.processSentEvent (AppletPanel.java) at
com/ms/applet/AppletPanel.processSentEvent (AppletPanel.java) at
com/ms/applet/AppletPanel.run (AppletPanel.java) at
java/lang/Thread.run (Thread.java)

This error is generated because the content transfer applets have tried to read a registry key that does not exist.

The solution is to manually create this missing registry key.

Launch Regedt32 and you need to create the following key :-

HKEY_Local_Machine/Software/Documentum/Common/CheckoutDirectory

The value for this key should point to the directory that you wish to use as the checkout directory for the content.