I solved this issue afterwards by doing steps below:
1. check your permission is Read&Write
1.1 Finder-Go-Home (or Shift-Command-H)
1.2 mouse right click, and select Get Info
1.3 find Sharing&Permissions
1.4 make sure your privilege is Read&Write
some users may find the issue has been solved when they correct the privilege. But in my case, my permission setting was correct. So here is what I do:
2. open terminal (Finder-Go-Utilities-Terminal)
and type
mkdir ~/.Trash
and it returns File exists
(make sure there is a space before~, the 1st time when I tried it, I forgot to leave a space, and it returned No such file or directory)
And then I type
sudo rm -ri ~/.Trash
and it will ask you to type your password, and return this question
remove /Users/xxxx/.Trash?
and I type
yes
what this does is to do a deep cleaning of the trash folder
Close the terminal. Wha-la, I am able to drag files to trash folder and put them back. When I delete a file, it will show in the Trash folder as well. Problem solved.
If you find that you have the same issue after a software update, you can try this to fix. In my case, I think it’s the update causes this error. This issue seems to happen to other users in the past, and apparently it is not a new thing. I have been using this MacBook Pro for 4-5 years, and just got this issue in 2018. The trashing thing didn’t act weird before. Maybe if you are lucky, you will get this bug. lol
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Reference from this site:
Files dragged to the Trash "will be deleted immediately" alert
http://www.thexlab.com/faqs/trash.html#Anchor-Files-46919