Idea: The "space" character may be literally represented as a % escape sequence (as in HTML). Perhaps that causes issues.

I haven't run across that problem myself. I have found a problem with annotation crashing in PDF documents when two very similarly named documents with very long names are added to the library.

We use a naming convention for computer documents here, like, projectnumber-projectname-documenttype-documentversion, so where multiple versions of a document exist only the last character of the filename may be different. It looks like the library's maximum file name lenght is shorter than allowed by FAT.

The first PDF document was added and annotated. A second document was added with only a change to the last couple characters of the filename. After attempting to save annotation in the second document annotation now crashes the reader for both documents whenever switching from annotation to reader modes.