Upon investigating a suspected bug for a user today, I found it was caused by the user's document in BookMacster having two folders with exactly the same name in the Reading List.
Short Version. If you get this error when exporting to Safari, see if you have two folders of the same name in your
Root or
Reading List or
Other Bookmarks. If so, change the name(s) so that all such folders have different names.
DetailsBecause Safari does not allow folders in Reading List, BookMacster remaps these into the Root level. Well, it turns out that macOS will not allow us to put two folders of exactly the same name at root level; hence the error
772030 Cannot create a new item (which refers to the second such folder) when we try to export such an arrangement from BookMacster, Markster, Smarky or Synkmark.
This behavior is due to some unexpected behavior in Safari, which we think is a bug, but maybe Apple thinks it is a feature. To reproduce this behavior, open Safari's
Edit Bookmarks create two folders with the same name, and put both at the root level. Then quit and relaunch Safari. One of the folders will have disappeared, and its contents will have been combined into the other folder. Or you can
watch me do it.
This behavior has been observed in macOS versions as early as 10.14.5 (spring 2019, with Safari 12.1.2), and as late as macOS 15.0 Beta 6 (August 2024, with Safari 18.0).