All connections to the Dropbox service are done using a secure connection (SSL). If you get a "Cannot establish a secure connection" error, check the following:
Is your system incorrect?
Your computer will compare your system date to the expiration date of our SSL certificate. If your system time is stuck in the past or so far in the future that it’s outside of Dropbox's SSL certificate expiration date, a secure connection can’t be established.
To correct this, change your system time to the current date (either on your computer, your router, or both).
Note: System time is different than the date/time that appears in the system tray or menu bar of your computer. Check the macOS or Windows help centers for more info.
Do you have a proxy or firewall blocking the Dropbox service?
Are your default proxy settings incorrect?
Some external software programs will change your computer's default proxy settings when installed and may not alert you of this. Confirm that your proxy settings haven't changed and, if you don't use a proxy setting, select the option for "No proxy."
You can also use the Dropbox Preferences menu to set Proxy settings:
On Windows computers, this error indicates there’s a problem with the permissions of your %TEMP% folder. This folder is used by Dropbox (and many other apps) for start up, install, and uninstall. To fix this issue, you'll need to give your user profile "full permissions" over the %TEMP% folder.
Change permissions for the %TEMP% folder
Note that permissions can be modified by other applications on your computer (in particular, software you've obtained from untrusted sources). If the permissions problem returns after restarting the computer, it means another program on your computer is making this change. Check your system permission logs if you know how, or take your computer to a professional to identify the program that's making the change.
If you see the error Try again or check out our Help Center, contact Dropbox support. Be sure to include as much detail as possible about what happened. For example, tell us what you were doing when the error appeared.
We regularly release new versions of the Dropbox app with new features, better performance, and security enhancements. These new versions are rolled out through automatic updates.
Certain conditions may cause these updates to fail. Failure to update can result from environment configurations, such as permission issues, or due to interactions with other applications, such as antivirus or firewall policies.
After a few failed attempts to automatically update, the Dropbox app displays the message “You’re using an older version of Dropbox.” To resolve this issue:
You may need to uninstall the Dropbox app before reinstalling if:
If the counter for updating your application expires, your Dropbox stops syncing. Click “Update Dropbox” to start the update process and continue using Dropbox.
If you’re part of a Dropbox Business team, it's possible that your auto-updates failed because your user profile on your computer doesn’t have the permission to install new versions of Dropbox. If the manual update fails, contact your IT admin for assistance.
If you receive the “Your computer is not supported” error, your computer may not meet our system requirements. To fix this issue, check that Dropbox is running on a supported operating system. If your operating system isn’t supported, update to a supported version.
Compatibility mode on Windows computers
If you’re using a Windows computer, check that compatibility mode isn’t enabled for Dropbox. To use the Dropbox desktop app on a supported operating system, disable compatibility mode.
If you receive the “Dropbox can't access your Windows Registry” error, it means Dropbox is attempting to access vital account information using your Windows Registry, but is being denied permission.
In most cases, it's possible that access to the registry is protected by the account credentials of an old or out-of-date user account. Resetting your Windows password should fix this problem.
Reset a Windows password
Once your password is reset, try reinstalling Dropbox. The installation should work without error. If this doesn't resolve the issue, then it's possible that some files in your folder have incorrect permissions.
Fix incorrect file permissions
attrib -s -h -r credhist
attrib +s +h credhist
If this doesn’t fix the error, you may need to manually remove the entry from the registry. Due to the sensitivity of the information in your Windows Registry, only those comfortable editing the registry should attempt this. You’ll also need admin rights on your computer to edit the registry.
Update Windows Registry
If you get an error that says "Can't delete ks key: error while deleting key,” you may need to add your group or user name.
Add group or user name to fix “Can’t delete ks key: error while deleting key”
Add yourself as an owner
Note that it's possible you’ll get an error when trying to add yourself as an owner. There are some objects in the registry that are impossible to change ownership of. The error message is expected behavior, and you can ignore the warning.
When installing Dropbox on certain versions of your operating system, you may see an error stating that "Dropbox is damaged and can't be opened."