Hi,
We have faced this issue earlier at one of the customer's end wherein few of the files were missing and we were getting exactly the same error message
Missing files are following below (This can't be same at your end, may verify but you can try the below steps to resolve the issue)
The following three files are not properly updated during the upgrade to 11.5:
\Vontu\Protect\lib\jar\es_common.jar
\Vontu\Protect\lib\jar\es_ecispi.jar
\Vontu\Protect\lib\jar\es_sharepointom.jar
Solution:
Perform one of the following to steps to allow the scans to work properly:
1) Uninstall and reinstall DLP 11.5 fresh on the Discover server.
2) Replace the JAR files mentioned above from another freshly installed server or with the attached files which are platform-independent (this option is ideal for a single-tier Enforce server).
I guess the first step should resolve your issue, hope for the best