I can't update my Dropbox email address to a Gmail address - Error 500 on opening link

I am currently trying to link my Dropbox account to my Google Account.

In order for this to work, my Dropbox Account needs to be configured with my GMail address, otherwise the accounts won't be linked.

However, whenever I try to update my email address and click the link that arrives in my GMail mailbox, I'll see the same error 500 screen:

Does anyone have an idea what I could be doing wrong? I noticed that Google is altering the link when I click it.
Instead of opening https://www.dropbox.com/l/[...] the tab will be opened as https://www.google.com/url?q=https://www.dropbox.com/l/[...]

Thanks in advance for any help!