Cannot use any of the functions

Hi I’m using the latest version and I’m getting this error. I can’t seem to do anything using ip

ERROR - 2017-09-21 12:44:28 --> Could not find the language line ""
ERROR - 2017-09-21 12:44:28 --> Could not find the language line ""

Here is a pic when I use the create user account function.

Please post the error logs of your web server. This might be a “deeper” problem so InvoicePlane does not log the actual error.