How to Flush the WSDL Cache

The WSDL cache is used for API soap calls to Magento. In some very rare cases this cache can get corrupted, causing errors on all API calls to Magento. In most of the cases this causes one of the following errors:

Resource path not callable
Invalid API path
Is not a valid method

This can be resolved in some cases by removing the WSDL cache file so this file is refetched with the next api call. To clear the WSDL cache, remove the cache files in /tmp:

rm /tmp/wsdl-*

NB: This does not solve the following error: SOAP error: Parsing WSDL: Couldn’t load from "": failed to load external entity. This error is related to Magento not being able to access its own API