Upgrade advice needed

[JWJ]

I've been reading a lot of threads about upgrading but can't answer my specific issue. I am running version 1.1.19 and the last time I tried to upgrade to 1.1.20 the package installation failed due to an issue with ./Sources/Subs-Package.php, which failed the Upgrade Test. Now I find that my host has upgraded php to 5.5 and I'm getting the preg_replace issues. It's clear I need to migrate to SMF2 but I've seen several threads pointing out the importance of having a 'clean' installation before attempting any migration. Can I migrate to SMF2 from my 'faulty' 1.1.19? Can I step back to 1.1.18?

I would very much welcome any advice as to the best way for me to proceed.
Thanks in advance.

[JBlaze]

Yes, you can upgrade to 2.0 from 1.1.19 easily. Upgrading to 2.0 from 1.1 means overwriting all the files, which means you will lose any mods and themes installed.

To be safe, make a file and database backup before upgrading, then follow the Upgrading SMF guide

[JWJ]

Thank you JBlaze, that's a big relief .... I was worried I might be in a catch 22 situation.