Upgrading PHP to version 7

[perryworld]

Hi,

We currently have a website running VirtueMart 3.4.2 and using php 5.6.38 on Joomla 3.9.0
We are getting a message about the php version but if we try to upgrade it to version 7.1.23 we get an error
OOPS, YOU'VE ENCOUNTERED AN ERROR - IT APPEARS THE PAGE YOU WERE LOOKING FOR DOESN'T EXIST. SORRY ABOUT THAT

Any help would really be appreciated

Thanks
Rich

[GJC Web Design]

You have to dig much deeper... this tells us nothing

find the error, turn on debugging, search logs etc etc .. all the standard debugging techniques, check u have all the necessary php modules enabled