Hey! Yes, a full drive can cause all sorts of issues for applications and especially for blockchain data that is continually incoming. Maybe do another review of your drive and remove or offload as much as you can elsewhere.
Once you have plenty of space, make sure your Syscoin wallet is closed. Locate your Syscoin data directory. Here is a guide to help you locate Syscoin’s data directory depending on what system/OS you have:
Once you find it, immediately backup these files: syscoin.conf, wallet.dat (or as many .dat files as you have there or in any child directories), masternode.conf (if you have masternodes). These should all be within Syscoin’s data directory.
Do not proceed without having safe backups of those files!
After you backup all those files to a thumb-drive or similar, you’ll need to delete the contents of the data directory, then copy your backed-up files into the directory once again. Then launch your Syscoin wallet which will then download all data afresh. Downloading the blockchain will take some time, so do be patient.