When I go to link Dropbox it quickly loads a login screen then switches to a blank screen titled Dropbox. Nothing happens and I am forced to hit cancel in the hupper left corner. This takes me back to the Adobe Dropbox login page. When there if I enter my Dropbox credentials it takes me to an Error (500) page apparently on Dropbox.com and I get an email from Dropbox with a one time security code. I am never asked to enter a security code anywhere within the Adobe app. Is this a bug or is there a solution?
Sorry for the delay in response.
Are you still facing this issue? If yes, try updating Reader/ Acrobat to the latest patch and see if that resolves the issue. You may also download updates manually using this link: Adobe software and product updates
If that doesn't work, try the steps given at solution # 2 in the link given below and try again:
If solution#2 doesn't work, try repairing Reader/ Acrobat by clicking repair installation under Help menu, reboot the machine and try again.
Feel free to update this discussion if you need any help.