I recently started receiving error code 5000 when calling the web services
Each SOLO Server author account is assigned a unique pair of encryption keys with a matching Encryption Key ID. For security reasons, a recent change in SOLO Server requires using an Encryption Key ID and matching encryption keys for the Author account that contains the product.
For ease of use, the Protection PLUS 5 SDK and ClientServices sample applications all use a generic Test Author account with its own Encryption Key ID. It is likely that you may have copied this data into your application and then changed the code to use your own SOLO Server account without changing the encryption keys.
In SOLO Server, you should go to Configure / Products, click the Actions button, and choose View Encryption Key Data and generate the encryption key that is specific to your account. Change your software to use this encryption key data instead of the one associated with the generic test account or another author account. Protection PLUS 5 SDK users can read more in this manual topic.
If you have existing customers in production who are experiencing this issue, please open a support ticket and provide a reference to the error code and your Author ID. We can provide a temporary workaround while you update your software.