Problem
This error message occurs:
<ConditionData> Validation Failure: Site Id is wrong </ConditionData>
Cause
The default DHL integration in Magento has been activated, which cannot be used for shipping from Germany.
Merchants shipping from Germany do not need, and in fact will not have a Site ID to enter into the configuration.
Solution
If you are shipping from Germany, you must install the DHL extension for Magento, which then must be configured in the section shown below.
Configuration for DHL shipping from Germany
For shipping from Germany, do not to enable Magento's default DHL shipping method (shown below). This will not work for merchants shipping from Germany. It is aimed at merchants in the USA.
Configuration for DHL in the USA