Cannot login, code 400

It is known that some users are seeing “Code 400” or “Code: 406” error when they try to log in to SeeYou Cloud. It looks like this:

or like this 

This problem refers to the inability of the software to reach the SeeYou Cloud through a secure HTTPS tunnel. There are two typical reasons for this problem to appear:

1. User is on a corporate (or private) network behind a restrictive Firewall 

Such networks often do not allow encrypted connection to external websites and servers such as the SeeYou Cloud. Companies will often have policies about what is allowed and what not from internal networks. This is how they protect their own sensitive data.

Solution: Try to access the SeeYou Cloud from an unencrypted network or computer which is not on the corporate network. Such networks are typically home networks and networks created with a WiFi hotspot from your smartphone. That way you can be sure that this is causing your problem. There is no real resolution to this problem. Your employer doesn’t want you to access external sites by HTTPS (or possibly at all). 

2. Anti-virus software scans HTTPS traffic

Lately the Anti-virus software packages have enabled functions for scanning the incoming HTTPS traffic. What this does is it creates an intermediate certificate which decrypts your HTTPS traffic, scans it for malicious code, then encrypts it back with their own certificate and forwards it to its destination (typically your browser). During this process the certificate chain is compromised. In internet security speak this is sort of like a “man in the middle” attach except this time you agree and trust the company who decrypts your HTTPS traffic. 

An example from Kaspersky:

Many (if not most) of the Anti-virus products have such feature now. It is typically disabled by default.

Solution: Think about what this feature does: somebody else is reading your encrypted traffic. If you trust them and understand what this means that could be ok. If you want to keep this feature in your Anti-virus software please write to us at so we can give you a resolution for this use case.

Updated on March 11, 2021

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