Could you please after the download is done verify your game cache? You can do this by following these steps that are found here:
https://support.steampowered.com/kb_article.php?ref=2037-QEUH-3335

Thank you!

Thanks for quick response. I tried verify game cache with 0 bytes downloaded so nothing has been downloaded. Well it seems my installation is not corrupted. This issue anyway occur only when I start up my PC then it gets latest update as it should but not every day the same update and then at first start of the game it crashes with error above. Second and other starts of the game are OK.

Is your arma 3 folder "read only"? Are you using SSD, HDD ? Where you have installed game?

I am using HDD and it is installed in different drive than Steam application but I have it this way installed from alpha version two years ago without problems until now. Yes Arma 3 folder is read only but on the other hand all folders of games in common are read only with out issues.

OK, can you give us some .rpt files? If you dont know where they are, go to [User name Folder]>Appdata>Local>Arma 3

http://feedback.arma3.com/how-to-user.html

I atteched two .RPT files for comparison. Yesterday I changed "read only" and today I did not get that 900MB update but for sure I will wait few days before I can be sure about it.

Jeezus Christ! How many mods are you using? :D Ita may be their fault - updater/launcher is checking them every time you launche the game. Some of them had be somehow secured against modify/update, and it was updating endless. As for now, try to move ALL mods to diferent folder, so launcher cannot detect them (only vanilla game should appear/launch) and check if that helps.

I miss some content from ArmA 2. That is all. Anyway no patch was downloaded today so it looks promising with that "read only" parameter.

Good to hear :)

Well, today my arma 3 from 1.52RC is updating again... downloading same update again....

My version 1.50 after one week is just fine with no updates. Maybe someone could investigate it what is going on with updates.

I got answer - they released today second RC update - that what was downloading. Problem is, PhysX on the previous was better - there wasnt rocket tanks....