The current supported version is go-opera 1.0.2-rc5 for both mainnet and testnet.
Go-opera older than 1.0.2-rc5
You should download and use 1.0.2-rc.5
Trouble shooting: Syncing error
If you're downloading a version older than 1.0.2-rc5, and thus you can't sync or you may get any errors, then please make sure you:
Stop the node
Remove the current (broken) datadir (the default datadir is located at ~/.opera)
Download and build the latest version go-opera 1.0.2-rc5
Run your node again in read mode
Version go-lachesis 1.0.0-rc0 or older is longer supported.
If your node is in go-lachesis 1.0.0-rc0, and you still have events before migration (block 4564024), then you have two options:
Run the node in rc0 version and let the node complete the migration (it takes 1hr or more depending on the machine specs). You can check your log to see the progress. After migration, the node will run normal.