How to downgrade firmware versions in SG 450?

I recently update my firmware to 9.308 to 9.312-8 and we are experiencing constant http proxy not running - restarted notifications every 1 - 2 hours. 

I just want to know if its possible to revert back the firmware from 9.312-8 back to 9.308? I'm using the appliance SG 450.

I would be tempted to re-install these Up2Dates using the "version change" trick - you might get lucky. In the following, you can copy and paste each block of code - no need to do a line at a time:

Download the Up2Date packages from the ftp site: from the command line as root:

cd /var/up2date/sys
wget http://ftp.astaro.com/UTM/v9/up2date/u2d-sys-9.308016-309003.tgz.gpg
wget http://ftp.astaro.com/UTM/v9/up2date/u2d-sys-9.309003-310011.tgz.gpg
wget http://ftp.astaro.com/UTM/v9/up2date/u2d-sys-9.310011-311003.tgz.gpg
wget http://ftp.astaro.com/UTM/v9/up2date/u2d-sys-9.311003-312008.tgz.gpg

• • • Confirm that each md5sum is correct by comparing the results of the following with the contents of the corresponding .md5 files at ftp://ftp.astaro.com/pub/UTM/v9/up2date:

      md5sum u2d-sys-9.308016-309003.tgz.gpg
      md5sum u2d-sys-9.309003-310011.tgz.gpg
      md5sum u2d-sys-9.310011-311003.tgz.gpg
      md5sum u2d-sys-9.311003-312008.tgz.gpg

      If there was any error in any file, rm that file and download again as in step 1.
  • Prepare the Up2Dates for installation in WebAdmin:
    

    /sbin/auisys.plx --showdesc

    Using the technique described in Version Change Trick, change the version to ' 9.308016'
  • Install in WebAdmin on the 'Overview' tab of 'Management >> Up2Date'

Did that cure the problem? If not, William's prescription is the only way to go. [:(]

Cheers - Bob

is there maybe a guide how to do this?

 i heard of a special sophos USB stick