Version Control Automatic Update Error processing site catalog

[FrankW]

VCRM version 2.1.x / HPSIM 4.2 with latest SP

For either manual or automatic updates, this error is generated: The automatic repository update failed because an error occurred while processing the download site catalog.

In the error details: Error for file: C:\hp\hpsmh\data\webapp-data\vcrepository\catalog.xml
Error code: 2147500037
An invalid character was found in text content.

I have renamed the two XML files in that directory and re-launch the update, but the same two files are downloaded and the same error message occurs. I do not believe that the condition is transient because I've been trying to get updates for a month or so at this point, and they always fail.

I have enough custom baselines and configured components in the respository that I would not consider deleting and re-installing the vcrm without checking everything else first.

Thank You.