This means that the maximum request body size ModSecurity will accept has been exceeded. The limit is configured in bits.
For example:
1 gigabit is 134217728
1 gigabyte is 1073741824 (or 8 times a gigabit, which is 134217728)
The default is 1 gigabit, or 134217728
Important Note: There is a hard limit in apache itself of 2Gb on 32 bit platforms. Apache supports file sizes greater than 2 Gb on 64 bit platforms where Apache is built with large file support. Versions of Apache that are not compiled with 64 bit offsets (large file support), or are operated on 32 bit platforms will have a 2GB maximum limit. This 2GB hard limit is not enforced by modsecurity nor is it something ASL establishes, this is an internal limit in apache. Keep in mind this is also request body limit, not a response body limit.
Atomic Secured Linux Users:
Change this setting in the ASL/AP GUI to the maximum value you wish to set.
MODSEC_REQUESTBODYLIMIT
Atomic Protector Users:
Change this setting in the ASL/AP GUI to the maximum value you wish to set.
MODSEC_REQUESTBODYLIMIT
Aum Users
Change this setting in /etc/asl/config to the maximum value you wish to set.
MODSEC_REQUESTBODYLIMIT
Then run this command as root:
aum -uf
Rules Only Users/Do It YourSelf Users
In your modsecurity configuration file, change this setting:
SecRequestBodyLimit
To the new limit you wish to set, and then restart your web server.