Why you get it!

Let us explain what is triggering such a message.

1) Token/Session expired

Each customer is getting a token when accessing the tigerVPN system. This token is required to authenticate you in our system and it's killed after the session expired. A token is handed out based on the IP address of the requester and the app must ask for a new token if you connect to a vpn server (especially because your IP will change). As an example: Let's say you are launching tigerVPN in your office, that moment, we generate a token for you based on that IP address. It will help us verify that nobody else is trying to impersonate you. When you put the app in the background, you leave the office and your phone switches to 3G/LTE, that very same moment, your IP changed. However, the tigerVPN system does not recognize this IP with the token the iOS app sends for authentication and denies the replies. While the app should tell you that your session expired, it actually tells you that your email and or password is wrong.  -  Update!  This has been changed with the last version of the iOS app.  In the current version of the app, the token refreshes automatically and in such cases as described above, the app will get a new token on its own by requesting one the moment you have switched from one network to another.The session will only expire if you have been offline for more that 24 hours  -  no network coverage or phone being closed etc. and you will be taken  to the login page. This is a security and safety measure that prevents anyone at any given moment to intercept or "impersonate" you against our system. It can be that your phone has been stolen, has been forgotten somewhere, it ran out of battery and it's not in your possession anymore, bottom line, if it's been offline for more than 24 hours, you will need to login again. 

What can you do?  Log back in.

2) Delay between API call and App

It might be that the reply from our API takes a bit longer and that's why the app interprets the response as "invalid" and throws that error.

What can you do? Logout, log back in. This should be rather temporarily. 

3) Unusual high load 

As old apps and new apps are currently generic more load on our network, it can be that they run in a so called "cached" replies.

Cached replies prevent the network to be flooded, that being said, it could cause some of the communication between API and APP to be slightly delayed which results in an error message as above. 
What can you do? Similar to the above, we suggest to give it a couple of seconds and try it again.