Windows 7: unable to register DLL – Error Code:0X80004005

Find JDK Installation Directory

First you need to know the installation path for the Java Development Kit.

Open the default installation path for the JDK:

C:\Program Files\Java

There should be a subdirectory like:

C:\Program Files\Java\jdk1.8.0_172

Note: one has only to put the path to the jdk without /bin in the end (as suggested on a lot of places). e.g. C:\Java\jdk1.8.0_172 and NOT C:\Java\jdk1.8.0_172\bin !

Set the JAVA_HOME Variable

Once you have the JDK installation path:

1. Right-click the My Computer icon on your desktop and select Properties.
2. Click the Advanced tab, then click the Environment Variables button.
3. Under System Variables, click New.
4. Enter the variable name as JAVA_HOME.
5. Enter the variable value as the installation path for the Java Development Kit.
6. Click OK.
7. Click Apply Changes.

Note: You might need to restart Windows

The complete article is here, on my blog: Setting JAVA_HOME Variable in Windows.

I finally found the answer (I haven't noted my source but it was from a search);

While the code works in Windows XP, in Windows 7, you must add this at the beginning:

// using System.Net;
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
// Use SecurityProtocolType.Ssl3 if needed for compatibility reasons

And now, it works perfectly.

ADDENDUM

As mentioned by Robin French; if you are getting this problem while configuring PayPal, please note that they won't support SSL3 starting by December, 3rd 2018. You'll need to use TLS. Here's Paypal page about it.