This is a known issue affecting VMware vSphere versions 6.5, 6.7, and 7.0.
Currently, there is no resolution.
Workaround:
To work around this issue, use one of these options:
- Reduce the number of scheduled tasks to 100 or less.
OR
- Search for task named "VMware vSphere Update Manager Update Download" in vCenter > Configure > More > Scheduled Tasks and see "Last Run" and "Next Run".