Thank you. I was able to solve the problem. However, I was a little concerned…
“Update failed: This site has encountered a serious error. Check your site administrator’s email inbox for action steps. See here for wordpress troubleshooting.”
Displayed as above.
I don’t receive emails when there is no actual problem, so I think it’s simply a display problem.
I don’t know if it’s just me or if other people have the same problem, but I’ll report it anyway.
For the time being, the “Site health status problem” of the main subject has been solved.
I’m really thankful to you.