Thank you, my friend, for your interest and help. After I did not receive a response to the topic yesterday, I did the following.
I installed PrestaShop version 8.1.2, and then I encountered error messages when I tried to log into BackOffice. I did not succeed in solving the problem. Then I uploaded the full file of the store to FTP for version 1.7.9.10, and now this message appears when I try to login to BackOffice:
If I get BackOffice back, I will apply what you suggested as a solution to the problem