Getting error “this.wss container is null “when started using new ready api 5.7

You’re hitting a known edge case: you’re trying to open a ReadyAPI project in SoapUI Open Source 5.7.1 (the 5.x line is SoapUI OS, not ReadyAPI). Projects that contain WS-Security config can throw

DefaultWssContainer.resolve(...) because "this.wssContainer" is null

during import/resolve. It’s a SoapUI OS bug/mismatch when a project created in ReadyAPI has WS-Security sections the OS resolver doesn’t initialize.

The easiest way to take care of this if to strip WS-Security before import.
Open the project in your older ReadyAPI (or any version that loads it), then:

• Project → WS-Security: delete outgoing/incoming configs and cryptos used by the project.
• In each SOAP request: clear the Outgoing WSS assignment.
• Save, then import that trimmed project in SoapUI OS.
  This avoids the OS resolver touching a missing wssContainer. Community threads reporting the exact NPE confirm the WS-Security container is the trigger.

Let me know if this helps!

Unable to Import ReadyAPI project to SoapUI | SmartBear Community