Missing files

[biojo]

Sometimes between the scan is taking place, there might be a tempory file created when main file is open

but when the program is closed it removes the temp file, but FreeFileSync believe its should have needed to copy it.

In scenerios where the file has been removed by the time it comes to copy it can it be set to, auto ignore these

[Plerry]

If those temp files can be recognized by their name, you can use the Exclude Filter.
See e.g. here.

[biojo]

this was going to be my solution but dont know if there always the same name yet, and dont want to just ignore all *.tmp etc at minute

[xCSxXenon]

this was going to be my solution but dont know if there always the same name yet, and dont want to just ignore all *.tmp etc at minute

Why? By definition, tmp files aren't necessary long-term, so there's no reason to save them

[biojo]

I just need to check whats in the folders, I know generally .tmp files arent required, but dont want to be too quick to remove them all

[xCSxXenon]

That is definitely a good idea, trust but verify. I can say that I have never had an issue with deleting any and all temp/cache files from thousands of customer computers over the years ¯\_(ツ)_/¯
Been part of my regular cleanup process for as long as I can remember