So, I finally decided to upgrade to Ubuntu 15.10, only to discover kdenlive was uninstalled in the process, and I need one final render.
Now rendering crashes with "Rendering of <filename> crashed

/usr/bin/melt: symbol lookup error: /usr/lib/frei0r-1/colgate.so: undefined symbol: lrintf"

Any help would be appreciated...

https://kdenlive.org/node/9460 -- Kubuntu packagers unfortunately did a non-plus job with respect to Kdenlive, MLT, frei0r, and ffmpeg to put it mildly...

Any suggestion on how to fix this?

See the link and read the post, try the stable ppa.

I did install kdenlive from the stable ppa.

Thanks for your report. There seems to be an issue with the way we built the Frei0r packages on our PPA, I have sent a patch proposal and hope to have it fixed in the next days, regards

jbm wrote:Thanks for your report. There seems to be an issue with the way we built the Frei0r packages on our PPA, I have sent a patch proposal and hope to have it fixed in the next days, regards

Looks like everything is back to normal: thanks for sorting this out!