They absolutely should, and the process creates a copy in version 1’s format for safety. However, if you want to test it, you can install the trial of version 3 (which just lacks a license to make it the full version) in a separate location from the original version 1 installation. Essentially, just tell the installer to change the install folder name to add a “3” at the end of its suggested folder name.
Once you have both versions installed, you can just use version 3 to open your version 1 projects. It will create a backup copy (adding “copy” to the end of the .scriv folder name) in the old version 1 format, and then convert the original to version 3’s format. If anything goes wrong with the conversion, you can open the “backup’” copy in version 1.
On the Mac side, I didn’t have any issues with the transition after converting every project. I’ve seen a few posts here and there about some projects that won’t convert without some fiddling, so it’s helpful to have both versions available until you’ve successfully converted all of your projects.
Definitely helpful to keep both versions available. From what I’ve seen, there are three main categories of conversion problems:
Extremely old projects, last opened in Mac Scrivener 2.5 or earlier, may require a two-step conversion. This is less of an issue on the Windows side for obvious reasons.
Scrivener 3 has more robust checks for potential synchronization issues. This means that a project may report file conflicts when converted. The conflicts were already there, the older version of Scrivener just failed to detect them.
Closely related to this, any issue that keeps the project from opening normally will also impede the conversion. In particular, “missing” files can result if part of the project is stored exclusively with a cloud service.
If you run into any issues, feel free to open a support ticket, here:
When you’re installing, you will be given the option to change the folder where it’s installed, which is important; you can’t put them both into the same C:\Program Files\Scrivener\ folder, so if you’ve already got version 1 installed, tack a 3 onto that last folder name (C:\Program Files\Scrivener3) when installing version 3. Note that your full path from C:\ on will likely be somewhat different from my example; the important bit is to give the Scrivener folder a name specific to the version you’re installing.
Also of note, only one of them will be the default program that tries to open a project when you double-click on it in the Windows file browser, probably the last one you installed. To use the other one to open a project, you’ll need to launch that version of Scrivener and open the project from Scrivener’s menus.