Did you change the drop-down menu under the Book settings panel (top right)
There are three choices
...yes, I selected PDF, which is how I got the option to Export Book to PDF.
In case I wasn't clear enough before: I tried JPG first, but was not happy that I couldn't export spreads together. So I switched to trying the PDF option, which is when I ran into the other two problems.
I suppose a further bit of info could be handy: when I did first export as JPG, I did not get this error - all of the photos rendered ok. I just wanted the spreads to be together, so I tried the PDF option, hit Export Book to PDF, and got the render error. Same photos, same everything, just different export format.
Aha! So here is some more more info. Turns out my original problem #2 is related to problem #3.
If I select a Color Profile like sRGB then I can export as a PDF without the error.It hasn't completed yet, but it looks like it's working - it's well past where it threw the errors before.
I had left the Color Profile set to "Other..." in the hopes of somewhere being able to select a different color space, and that seems to be what is causing the "cannot render" error. Makes sense - the engine has to render the files in some color space, but one hasn't been selected.
So that seems to be a bug in Lightroom somehow - that the "Other..." doesn't work correctly and the error message isn't useful - but at least my problem #3 has a workaround.
Now: how do I get my PDF into CMYK as the print shop requires without losing control over the conversion and losing quality?
- Export as Pro Photo RGB or Adobe RGB.
- Open in Acrobat(?)
- Re-save / re-export.
Ask your print lab if it can convert it. CMYK is used mainly for commercial offset printing e.g. magazines and brochures. It's a much smaller color gamut so it should be possible to convert from ProPhoto RGB or sRGB.
Selecting "Other..." from the Color Profile should open a dialog box. this box will list all compatible color profiles on your computer (print only by default, but you can choose to include display profiles as well). In this dialog box, you put a check mark next to the profiles you want to use. After clicking OK, these profiles will now appear in the list of Color Profiles along with the defaults (sRGB, Adobe RGB, and Pro Photo RGB).
Our big question is why are you not seeing this dialog box? Perhaps there are profiles installed on your computer which are not compatible with Lightroom and when LR tires to read the list it cannot display the dialog?
Right, that would be the expected behavior. But if PDF is selected there is no dialog box.
If I select JPG and Color Profile: Other... then I do get a dialog box and a list of installed profiles, so Lightroom is able to pull them up.
I haven't actually done too much printing from this computer - I usually print elsewhere - so I don't have too many profiles installed - a few Epson paper profiles, in addition to the Display Profiles.
If you think it's helpful I could delete them and try again, but since if JPG is the "Book type" and the "Other..." dialog does pop up, I'm not sure it would enlighten much?
In any case, I think as long as I can get an export in a good color profile, which I now am able to do, then I think I can deal with color space down the road (correct me if I'm wrong on that). If you want me to help troubleshoot the dialog box let me know!