Tech Support section is for getting help with FTB related problems.
If there's a repeatable issue that can be labeled as a bug, then please use the issue tracker for the pack or the app at GitHub issue trackers
- If there's no repository for a pack that means that the pack is old and/or will not be updated. Bugs for older packs will not be fixed, unless they are critical.
This is a problem with a mod doing something with an async method improperly. Try loading a backup of this world. Or if you don't care about the world delete it and make a new one.