upgrade path from 1.5.x to 2.9.x

I think this is what you’re looking for:

https://codex.www.ads-software.com/Upgrading_WordPress_Extended#Detailed_Upgrade_Instructions_for_1.5.x.2C_and_versions_2.0_-_2.6.5.2C_to_2.9.2

Thanks! …does this mean it is only one update step?
I just need to upload v 2.9.2 and can leave out all the intermediate versions?

I believe so. It’s a little bit more complicated than the standard upgrade procedures, but you should be able to go from 1.5.1.3 directly to 2.9.2. Backup your database first, just in case.

https://codex.www.ads-software.com/Backing_Up_Your_Database

I’d suggest something like 1.5 -> 2.2.1 -> 2.3 -> 2.5 -> 2.7 -> 2.9.x

Thanks!
I’ll try that one…

I’d suggest something like 1.5 -> 2.2.1 -> 2.3 -> 2.5 -> 2.7 -> 2.9.x