This indicates that you may not have your game updated to the latest version of the game. First, make sure that you are launching the game from the launcher and not from the .exe file. If the issue persists, proceed to the following steps:
Why am I receiving Error 500 (3:1:1268:0) "Data version does not match the client version. Please make sure the game is fully up to date"?

goatlyonesub17_ESO wrote: »Update. 6:14 UTC on 2 December 2020. The worst possible scenario. I had been at (about) 92% on the big download when the electric power flickered again, causing my computer to reboot and breaking the download. I will have to start all over again. More than two weeks of downloading time wasted.
goatlyonesub17_ESO wrote: »That is a good suggestion. I may be able to buy one on Amazon and have it shipped to me. In fact, I already have a battery backup: my monitor is standing on top of it. However, it is old and today it functions only as a socket multiplier. It doesn't supply current anymore when the power goes out.
I've never had this much bad luck before with downloading ESO. I did the original downloading in 2014, of course. And I had to redownload everything when ESO began requiring Flash 12, and my computer could only run Flash 11. (I had to buy a new computer that time; it cost me $1500.) But the downloading was successful in only a few tries.
Anyway, something odd happened this morning about 8am EST or 13h UTC (approximately, I didn't see exactly when it happened). Overnight, I downloaded the first 2% of the big 57gig file. Something happened to reset the download back to the beginning. The computer didn't crash. The launcher didn't crash. The electricity didn't go out. But I lost the first 2% of the file that I had downloaded during the preceding 13 hours.
So, technically, I suppose you could say that I'm on download attempt #8, even though I can't pinpoint the time at which it began.
goatlyonesub17_ESO wrote: »It happened again! Just now, at 21:10 UTC on 8 Dec 2020, my download progress (8th attempt) hit 2% and then, suddenly, that progress went away and the download restarted from the beginning. I don't know what to do now.