[J_B]

Hello GRiker,
I have exactly the same problem as AzureRyuu.
When you said it'd be a problem with an author field, I could narrow it down.
I was able to create catalogs for all authors, except the ones whose "Author Sort" start with a number.

I made a little test epub and it confirmed it:

author: abcd 1

Spoiler:

Erstelle Katalog
Sections: Authors, Titles, Series, Recently Added, Descriptions
Catalog_EPUB_MOBI(): Generating epub for generic_eink in GUI environment
converting empty exclude_genre to '\[^.\]'
connected_device: 'None'
book count: 1
opts:
authorClip: 100
catalog_title: u'autoren_test'
connected_kindle: False
descriptionClip: 380
exclude_book_marker: u':'
exclude_genre: u'\\[^.\\]'
exclude_tags: u''
header_note_source_field: ''
merge_comments: '::True'
output_profile: 'generic_eink'
read_book_marker: u'tag:+'
search_text: None
sort_by: None
sort_descriptions_by_author: True
sync: True
thumb_width: u'1.00'
wishlist_tag: u'Wishlist'
existing thumb cache at C:\Users\J_B\AppData\Roaming\calibre\caches\catalo g\thumbs.zip, cached_thumb_width: 1.00"
Begin catalog source generation
DPI = 168; thumbnail dimensions: 168 x 224
using default cover for 'catalog test' (2993)
no series found in selected books, cancelling series generation
Python function terminated unexpectedly
need a single Unicode character as parameter (Error Code: 1)
Traceback (most recent call last):
File "site.py", line 132, in main
File "site.py", line 109, in run_entry_point
File "site-packages\calibre\utils\ipc\worker.py", line 192, in main
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 68, in gui_catalog
File "site-packages\calibre\library\catalogs\epub_mobi.py", line 306, in run
File "site-packages\calibre\library\catalogs\epub_mobi_builde r.py", line 517, in buildSources
File "site-packages\calibre\library\catalogs\epub_mobi_builde r.py", line 2640, in generateNCXByAuthor
File "site-packages\calibre\library\catalogs\epub_mobi_builde r.py", line 3836, in generateUnicodeName
TypeError: need a single Unicode character as parameter

When I changed the author name to abcd_1, the catalog was created just fine:

Spoiler:

Erstelle Katalog
Sections: Authors, Titles, Series, Recently Added, Descriptions
Catalog_EPUB_MOBI(): Generating epub for generic_eink in GUI environment
converting empty exclude_genre to '\[^.\]'
connected_device: 'None'
book count: 1
opts:
authorClip: 100
catalog_title: u'autoren_test2'
connected_kindle: False
descriptionClip: 380
exclude_book_marker: u':'
exclude_genre: u'\\[^.\\]'
exclude_tags: u''
header_note_source_field: ''
merge_comments: '::True'
output_profile: 'generic_eink'
read_book_marker: u'tag:+'
search_text: None
sort_by: None
sort_descriptions_by_author: True
sync: True
thumb_width: u'1.00'
wishlist_tag: u'Wishlist'
existing thumb cache at C:\Users\J_B\AppData\Roaming\calibre\caches\catalo g\thumbs.zip, cached_thumb_width: 1.00"
Begin catalog source generation
DPI = 168; thumbnail dimensions: 168 x 224
using default cover for 'catalog test2' (2994)
no series found in selected books, cancelling series generation
Completed catalog source generation

InputFormatPlugin: HTML Input running
on C:\Users\J_B\AppData\Local\Temp\calibre_0.8.62_tmp _c7uxw9\vyuhcs_epub_mobi_catalog\Catalog.opf
Parsing all content...
Merging user specified metadata...
Detecting structure...
Flattening CSS and remapping font sizes...
Source base font size is 12.00000pt
Cleaning up manifest...
Trimming unused files from manifest...
Creating EPUB Output...
Splitting markup on page breaks and flow limits, if any...
Looking for large trees in content/ByAlphaTitle.html...
No large trees found
Looking for large trees in content/ByAlphaAuthor.html...
No large trees found
Looking for large trees in content/book_2994.html...
No large trees found
Looking for large trees in content/ByDateAdded.html...
No large trees found
Generating default cover
EPUB output written to C:\Users\J_B\AppData\Local\Temp\calibre_0.8.62_tmp _c7uxw9\wih68m_catalog_out.epub

I hope this helps.