Defraggler v2.21.993 (64 bit) crashes

I set up scheduled defrags on all partitions. All scheduled runs crash with a report like this:

Faulting application name: df64.exe, version: 2.21.0.993, time stamp: 0x56d56a4e
Faulting module name: df64.exe, version: 2.21.0.993, time stamp: 0x56d56a4e
Exception code: 0xc0000005
Fault offset: 0x0000000000002b90
Faulting process id: 0x32c4
Faulting application start time: 0x01d2822c161fc0c4
Faulting application path: C:\Program Files\Defraggler\df64.exe
Faulting module path: C:\Program Files\Defraggler\df64.exe
Report Id: 4d9cf043-3763-4c92-b5aa-a86db01d5c0d
Faulting package full name:
Faulting package-relative application ID:
The Exception code and Fault offset are the same in each report.