Bitrix: fail to upload files larger than 4MB

Symptoms

During Bitrix self-testing, a test upload of files larger than 4 MB fails with the following error:

Uploading a file larger than 4MB (check_upload_big): Fail

Solution

Check the following parameters, their values must be set to more than 4 MB:

1. memory_limit, post_max_size, and upload_max_filesize in the target site's PHP settings;
2. client_max_body_size in the Nginx configuration file at /etc/nginx/nginx.conf;
3. FcgidMaxRequestLen in the Apache configuration file at /etc/apache2/apache2.conf (/etc/httpd/httpd.conf for RHEL-based systems).