The #bugs-and-feedback on the Foldit Discord server is the easiest way to upload log.txt or similar files.
There's a Discord link on the front page (fold.it) to get started.
In Discord, you can upload a file by just opening the #bugs-and-feedback channel, and dragging the file there.
Over here, uploading is a little trickier. Here in the forum area, you can't attach files, so no log.txt.
You can attach files in the feedback area, but they must be in a reply. So you must open a new feedback, then create a reply containing your file.
Uploading images to fold.it have been broken for a long time. The "game/var/www/lighttpd/portal" message is familiar.
A new Foldit website is in development. It may fix image upload and other problems.
Discord is good about images and other file types.
If Discord isn't an option for some reason, you can copy just the "traceback" lines at the end of log.txt and a few preceding lines, and paste them in here.
In a best case scenario, the traceback lines look something like this:
UNHANDLED EXCEPTION
****** Encountered Crash at Unknown File:0
Unknown Exception
1: interactive::application::shared::ToolActionBridgeMixin::create_and_launch_bridge_action +64 bytes (no line)
2: interactive::application::tools::SelectionTool::motion_callback +151 bytes (no line)
3: interactive::util::detail::checked_fxn_wrapper<bool (__thiscall interactive::application::tools::SelectionTool::*)
(interactive::util::owning_ptr<interactive::application::shared::ToolResidueSelection const >,
interactive::util::access_ptr<interactive::poseview::NewMotionControlGeom>)>::operator()<interactive::application::tools::SelectionTool,
interactive::util::owning_ptr<interactive::application::shared::ToolResidueSelection const > &,interactive::poseview::NewMotionControlGeom * &,
bool (__thiscall interactive::application::tools::SelectionTool::*)(interactive::util::owning_ptr<interactive::application::shared::ToolResidueSelection const
>,interactive::util::access_ptr<interactive::poseview::NewMotionControlGeom>),0> +110 bytes (no line)
4: boost::detail::function::function_obj_invoker3<boost::_bi::bind_t<boost::_bi::unspecified,interactive::util::detail::checked_fxn_wrapper<bool (__thiscall interactive::application::tools::SelectionTool::*)(interactive::util::owning_ptr<interactive::application::shared::ToolResidueSelection const >,interactive::util::access_ptr<interactive::poseview::NewMotionControlGeom>)>,boost::_bi::list3
<boost::_bi::value<interactive::util::access_ptr<interactive::application::tools::SelectionTool> >,boost::_bi::value<interactive::util::owning_ptr<interactive::application::shared::ToolResidueSelection const >
>,boost::_bi::value<interactive::poseview::NewMotionControlGeom *> > >,bool,numeric::xyzVector const &,numeric::xyzVector const &,double>::invoke +38 bytes (no line)
5: boost::function3<bool,numeric::xyzVector const &,numeric::xyzVector const &,double>::operator() +139 bytes (no line)
6: interactive::poseview::NewMotionControlGeom::do_z_rot +975 bytes (no line)
</pre>
I added the html tags <pre> before and </pre> after those lines to make them a little easier to read.
The traceback information isn't always present after a crash, or it may contain "no symbol" errors.
(Edit: broke up some long lines....)