So there are several reasons for file corruption.
1 - Storage Issues (Most Common)
Bad sectors on your HDD or SSD, power loss while writing/reading data, or just wear and tear of your HDD/SSD over time. No idea how old your system is, but judging by the specs, you are definitely on the lower end of the spectrum here.
2 - Software Conflicts & Bad Updates
It’s very possible the patch/update you installed was interrupted during installation, or an antivirus program messed with it (not likely), or steam/blizzard’s patching just failed to do its job. Running the scan+repair tool should help fix this issue, or the ‘check integrity of files’ for steam, or whatever it is.
However if this is a consistent problem, I’m more inclined to believe it’s your system, and not the updating itself that is causing your issue.
3 - Hardware Instability
This could be faulty RAM, overheating of the CPU or GPU, even PSU problems where it’s not giving out enough power, or worse having sudden power loss, this is harder to diagnose, as you’d have to go through some specific testing.
4 - Disk Write Failures
This could be a sign your HDD/SSD is actually failing as mentioned in #1. If it has a bad sector, wear and tear, or sudden power loss, this will cause you more issues as time progresses, not just for this game mind you, but your whole system.
I would say it’s also an issue when using an external drive and unplugging it improperly, but that doesn’t seem to be the case here.
5 - Lower Than Required Specs
If your system is failing to meet the requirements it could very well cause corruption to some degree, but this is mostly due to crashes, BSOD issues, etc.
Conclusion - I believe it’s more of a hardware issue, if at all possible, I would say if you have another SSD, to transfer the files over to that separate drive and try it again. Just to rule out it’s not your SSD at least, it very well could be another piece of hardware, but this is where I would start.