I can't upload files (Apache)

I have a Symfony app running on docker exposing the port 8000, then I proxy the requests from my domain to http://localhost:8000/ it works well but when I want to send files using multipart/form-data it returns a 500 error code without more information, if I make the request directly to http://my_ip:8000 it works fine so I think it is a proxy error.

I checked apache errors.log and I get this error

[http:error] [pid 140227] [client 190.55.60.91:4255] AH02429: Response header name 'PHP message' contains invalid characters, aborting request

This is my apache config:

<VirtualHost *:80>
        ProxyPreserveHost On
        ProxyRequests Off
        ServerName mydomain.com
        ServerAlias mydomain.com

        SetEnv proxy-sendchunked 1

        ProxyPass / http://localhost:8000/
        ProxyPassReverse / http://localhost:8000/
        SetEnv proxy-sendchunks 1
        ProxyTimeout 1000

</VirtualHost>

<IfModule mod_ssl.c>

       <VirtualHost *:443>

                ProxyPreserveHost On
                ProxyRequests Off

                ServerName my_domain.com
                ServerAlias my_domain.com

                ProxyTimeout 60
                ProxyPass / http://localhost:8000/
                ProxyPassReverse / http://localhost:8000/

                ErrorLog ${APACHE_LOG_DIR}/error.log
                CustomLog ${APACHE_LOG_DIR}/access.log combined
                SSLEngine on

                SSLCertificateFile      /etc/ssl/private/my_cert.crt
                SSLCertificateChainFile /etc/ssl/private/ca-bundle-client.crt
                SSLCertificateKeyFile /etc/ssl/private/my_cert.key

                <FilesMatch "\.(cgi|shtml|phtml|php)$">
                                SSLOptions +StdEnvVars
                </FilesMatch>
                <Directory /usr/lib/cgi-bin>
                                SSLOptions +StdEnvVars
                </Directory>

        </VirtualHost>
</IfModule>

I tried to add some properties like "SetEnv proxy-sendchunked 1" and "ProxyTimeout 1000" but it still not working.