Hello cmarangon,
that is a strange error pattern. You can try deleting the header already set by PHP. However, this only works if the header has not yet been sent. To do this, open the defaults.php file in the blog root directory. In the second line, insert the following:
Code: Select all
if (!headers_sent()) {
foreach (headers_list() as $header) {
header_remove($header);
}
}
If this does not work, check the server configuration (apache.conf or nginx.conf). The header may already be defined here. If it is an Apache web server, rename existing .htaccess files as a test (e.g. dot_htaccess).
It may also make sense to update from FlatPress 1.2.1 to FlatPress 1.3.1.
https://www.flatpress.org/download
With best regards
Frank