Pink thumbnails created by BUG-000129503 cause the WebGIS DR tool to fail at later versions, and return the following error message, "{"code":500,"messages":["Export operation failed. Unsupported Image Type"],"status":"error"}", after upgrading ArcGIS Enterprise from 10.6.1 to a newer version.

Workaround

If the software is upgraded and this problem of corrupted thumbnails is encountered, refer to the following tech article, https://support.esri.com/en/Technical-Article/000024415 to fix the thumbnails. Once the thumbnails are corrected, the WebGIS DR tool and other commands may have failed due to a corrupted thumbnail work.

However, the workaround mentioned in https://support.esri.com/en/Technical-Article/000024415 does not fix the issue if the images are referenced in esriinfo\metadata\metadata.xml and extracted\esriinfo\metadata\metadata.xml. If for a base64 encoded image and the info attribute is empty, the Export Site operation may fail after applying the workaround. Upgrade to version 10.9.x to fix the issue. 

Steps to Reproduce