Data-Driven Subscription result error

Hello,

I've created a data-driven subscription for a report which emails a specified user that I've manaully entered into the To field.  The report has a parameter which is included in the data-driven subscription.  When the subscription is applied and ran, it results in an error.  The error is very vague in that it says, "Done: 1 processed of 1 total; 1 errors."  To find the cause of this error,  on the Report Server server, I've checked the logs of the RSHostingService and RSPortal log files.  In the RSHostingService log file, I only see this error: WARN|17|Exception deleting expired log fileSystem.IO.IOException: The process cannot access the file '\Microsoft Power BI Report Server\PBIRS\LogFiles\msmdsrv.log' because it is being used by another process.  In the RSPortal log file, I do not see any errors.  Are the RSHostingService and RSPortal log files the correct locations to find the error log for a data driven subscription?

My Report Server is on the May 2020 version.