Problem in using Biblatex

Question

I have problems in using Biblatex, when I compile when file, the references are not shown and an error message of "empty bibliography" is shown.

Then I tried find a biblatex template provided by the overleaf platform. The following is the link of the template I found. https://www.overleaf.com/latex/examples/bibliography-management-biblatex-with-biber-backend/dpthxhwcfjtg I open the file in overleaf, and everything works fine when I compile the file, I can see the references and citations correctly.

Then I tried to delete the contents of the .bib file, and then I compile, a message of "empty bibliography" is shown. This is also ok, because the .bib is blank.

However, when I put back the contents to the .bib file, and compile, the message of "empty bibliography" is shown again, and no referencing can be seen.

I tried the same procedure in two different computers (with the same overleaf account), and the same problem appears.

I would want to know how to fix the problem. Thank you in advance.