413: FULL head when pushing to Mercurial repository behind Nginx
The problem is the header buffer of the application server, this is because of mercurial uses very big headers. You have to increase the size of the header buffer and this application server specific. In case you are using the standalone version, you have to edit the server-config.xml and increase the requestHeaderSize value.
replace:
<Set name="requestHeaderSize">16384</Set>with:
<Set name="requestHeaderSize">32768</Set>Source: https://groups.google.com/forum/#!topic/scmmanager/Afad4zXSx78