At the present time, iScreensaver Designer 5.2 provides support for macOS 10.13 High Sierra, but there are some functional limitations.
Please read the 10.13 High Sierra Tech Note
as well as the Release Notes
Due to changes made by Apple, iScreensaver Designer version 5.2 does not currently support macOS 10.14 Mojave.
Please read our forum post
for the latest updates.
[Solved] iScreensaver Crashing upon Launch
iScreensaver Personal, or iScreensaver Designer 126.96.36.1998 crash about 1-30 seconds after launch.
iScreensaver is crashing while scanning your iTunes or iPhoto library
1. Open iScreensaver.
2. from the iScreensavermenu, choose Preferences (tip: or, you can hold down the Command key and press the Comma key)
3. Uncheck the "Metadata Import: Use iPhoto library" and/or "Use iTunes library" checkbox(es)
4. Click OK
5. Quit and restart iScreensaver
We have only had reports of this happening using OS X 10.10.1 but if it happens to you, please contact us.