Thank you for the answer, I was only able to find time and refresh the files from my work.
Yes, when I threw the files again, the backup screen started to open, but I still get different errors in the customsert module. When I say edit the private certificate, the following errors appear on the screen above and below the certificate editing page.
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line 112 of /mod/customcert/view.php: call to mod_customcert\report_table->__construct()
get_user_field_name() is deprecated. Please use \core_user\fields::get_display_name() instead
line 3373 of /lib/deprecatedlib.php: call to debugging()
line 82 of /mod/customcert/classes/report_table.php: call to get_user_field_name()
line 112 of /mod/customcert/view.php: call to mod_customcert\report_table->__construct()
Footer
get_extra_user_fields() is deprecated. Please use the \core_user\fields API instead.
line 3331 of /lib/deprecatedlib.php: call to debugging()
line 263 of /mod/customcert/classes/certificate.php: call to get_extra_user_fields()
line 204 of /mod/customcert/classes/report_table.php: call to mod_customcert\certificate::get_issues()
line 2091 of /lib/tablelib.php: call to mod_customcert\report_table->query_db()
line 157 of /mod/customcert/view.php: call to table_
sql->out()
user_picture::fields() is deprecated. Please use the \core_user\fields API instead.
line 256 of /lib/outputcomponents.php: call to debugging()
line 264 of /mod/customcert/classes/certificate.php: call to user_picture::fields()
line 204 of /mod/customcert/classes/report_table.php: call to mod_customcert\certificate::get_issues()
line 2091 of /lib/tablelib.php: call to mod_customcert\report_table->query_db()
line 157 of /mod/customcert/view.php: call to table_sql->out()