Updating to a new version of Expression Engine gets harder as the amount of version dependant Add-Ons increase. I just successfully updated an expression engine site that had version dependencies.

Tip:  In most cases, when you buy an add-on you will receive both versions. It is important that you keep the original files.  Just because your site is in EE1 now, doesn’t mean you will not need access to the EE2 files in the future…  So make sure the account you use to buy and access your site’s Add-Ons are continually transferred to someone that can access them.  If not, you will need to buy all the Add-Ons again, which can get pricey.

Some EE Add-ons that will not work with the update and my solutions:

1.) Field Frame Module  –  In EE1, this module was used to create custom fields for the data.  The functionality of this module is now part of the core functionality of EE2.
If you also have the Matrix module installed, I had a lot of errors showing up.  These were corrected by implementing the most recent versions of the Matrix Add On.

2.) Ngen field type  –  This was used together with the field frame module.  After updating to EE2, just change the ngen file types to be the EE2 “File” field type that automatically comes with your new EE2 installation.

3.) Find and replace  –  The EE2 version of this plugin is  Low Replace  (template tag usage must update to new plugin)

4.) In Segments  –  The EE2 version of this plugin is  Segment Search  (template tag usage must update to new plugin)

5.) SL Google map  –  The EE2 version of this plugin is  MX Google Maps.  This one is a little more tricky to convert as MX google maps stores the long/lat values in it’s own table.  This is unlike the SL google Map module that stores all data in one table field. The next version released will have more support in conversion steps, but until then you need to write your own script to update the tables.