I've been using rainlendar 2.10b114 for some time on Archlinux (64 bit). As long as I had curl version 7.23.1 installed, rainlendar worked. It just presented a warning
rainlendar: /usr/lib/libcurl.so.4: no version information available (required by rainlendar)
on startup, but started nevertheless.
Some days ago, I updated my system which increased the version of curl to 7.24. Since that time, I was not able to start rainlendar anymore. It always fails with the error rainlendar: /usr/lib/libcurl.so.4: version `CURL_OPENSSL_3' not found (required by rainlendar)
which is clearly related to the newer curl version.
Looks like there have been changes in curl, which do not yet reflect in rainlendar's code.
EDIT: According to this forum thread
some more people are having this problem.