I saved my modpack server to an instance and changed to another instance but when I swapped back to the original instance it started crashing while the server was starting. I'm not sure why as it was working fine before I swapped instances.
I attached the latest.log.
#Server Keeps Crashing During Startup
marble lodge
sudden violet
Take a look at that server log file. It is very unhappy. Cannot load any datapacks. Check that the "swapped back" restored the datapacks.