License server response has not passed data integrity check: Invalid signature format
Attempt to obtain license from the server leads to the error
Starting with the 2018.2.1 release of JetBrains IDEs (released in Q3 2018), products no longer obtain license tickets from the old versions of JetBrains license servers (versions prior to #16429 which was released on March 19, 2018). To find the version number of the license server you are using, look in the license server log or in the web interface.
Update the license server to the latest version by following the upgrade procedure.