Updating my mod breaks world save data?

Some times when i update my mod the server im testing it on stops showing up in the server list, and i cannot join the server, i have to delete the world save data to join the server again… Clearly this is an issue that doesnt happen to everyone, and i dont want to break anyones server when i publish the mod, but what am i doing wrong?

Every time this has happened the new version of the mod works perfectly in single player and will work on the server perfectly once i delete the save data.

Is this because i didnt press the reset GUID button when uploading/updating?
Is my mod corrupt somehow?

Last time this happened all i did was change an icon to an item, and make a small change to a custom particle effect.

Please, any suggestions or advice would be much appreciated!

Yep, looks like it was because I didn’t reset the guid when updating/uploading the mod