This error started to appear on Windows 10 after v1809 in a 64-bit build. The cause appears to be related to the DynamoRIO drsyms library, which WinAFL uses to look up target_offset from method name.

Currently, there are these workarounds:

• Download a recent DynamoRIO version (I tested with DynamoRIO-Windows-7.0.17914-0 from https://github.com/DynamoRIO/dynamorio/releases) and delete all instances of dbghelp.dll from your DynamoRIO directory

• Create a build that doesn't use drsyms (I'll add a cmake option to disable it soon)