Redmine

Hi

I'm trying to user my redmine server (Appache with passenger) behind a reverse proxy.
I'm running my redmine installation on https port 443

On my reverse proxy the configutaion is like this ( I anonymized the log information)

ProxyPass             /    https://X.Y.Z.T
    ProxyPassReverse      /    https://X.Y.Z.T
    ProxyPreserveHost     On

SSLProxyEngine        On
    SSLEngine             On
    SSLCertificateFile    /path-to-cert-file

Chen I try to access the redmine site through the proxy I get :

Bad Gateway
The proxy server received an invalid response from an upstream server.

apache logs on proxy says : (anonymized again)

[Thu Jun 09 14:08:37 2011] [error] (502)Unknown error 502: proxy: pass request body failed to X.Y.Z.T:443 (X.Y.Z.T)
[Thu Jun 09 14:08:37 2011] [error] (502)Unknown error 502: proxy: pass request body failed to X.Y.Z.T:443 (X.Y.Z.T) from A.B.C.D ()
A.B.C.D - - [09/Jun/2011:14:08:37 +0200] "GET /login?back_url=https%3A%2F%2Fhostname.domain%2F HTTP/1.1" 502 395 "-" "Mozilla/5.0 (X11; U; Linux i686; fr; rv:1.9.2.13) Gecko/20101206 Ubuntu/10.04 (lucid) Firefox/3.6.13"
A.B.C.D - - [09/Jun/2011:14:08:37 +0200] "GET /login?back_url=https%3A%2F%2Fhostname.domain%2F HTTP/1.1" 502 395
~

Any ideas
Has it something to do with "/login?back_url=https%3A%2F%2Fhostname.domain%2F"
what is this back_url ?

Thanks for any answer
regards
Laurent