@JonyIvy reported:
I found some error messages regarding CORS in the browser console that pointed to a problem with respect to http vs https. So I tried loading the page with https://depth.openseamap.org/#register and voilà, the captcha was loading! (I suppose the registration will now work, will try later.)
Maybe make sure all non-https requests are redirected to https on the web server, that should solve the problem.
@JonyIvy reported: I found some error messages regarding CORS in the browser console that pointed to a problem with respect to http vs https. So I tried loading the page with https://depth.openseamap.org/#register and voilà, the captcha was loading! (I suppose the registration will now work, will try later.) Maybe make sure all non-https requests are redirected to https on the web server, that should solve the problem.