Sometimes it is also due to authorization via HTTP, especially with regard to the REST API of WordPress. In this case the following snippet in the .htaccess helps:
<IfModule mod_rewrite.c>
RewriteCond %{HTTP:Authorization} ^(.*)
RewriteRule ^(.*) - [E=HTTP_AUTHORIZATION:%1]
</IfModule>
Sometimes it is also due to authorization via HTTP, especially with regard to the REST API of WordPress. In this case the following snippet in the
.htaccesshelps:<IfModule mod_rewrite.c> RewriteCond %{HTTP:Authorization} ^(.*) RewriteRule ^(.*) - [E=HTTP_AUTHORIZATION:%1] </IfModule>