Originally Posted by Croker
SplitError: Could not find reasonable point at which to split: The Beach.html Sub-tree size: 800 KB"?
Calibre splits up big HTML files on page breaks for the PRS-505. Does it make sense that this 800 KB html file has no chapters or other opportunities for page breaks? If so, then pick a few places for breaks and manually add them in Book Designer. If not, then Calibre's automatic chapter detection is likely failing. This should be obvious in Adobe Digital Editions (no chapters in the TOC). I think Calibre uses h1 and h2 as the default chapter detection marks, but this is customizable.