When running appium test script individually they run fine but when run them together they throw error

Question

I have a few test scripts in a folder. When I try running all of them I get the following error message.

self = <appium.webdriver.errorhandler.MobileErrorHandler object at 0x111183390>
response = {'status': 404, 'value': '{"value":{"error":"invalid session id","message":"A session is either terminated or not started...eadableNT (_stream_readable.js:1168:12)\\n    at processTicksAndRejections (internal/process/task_queues.js:77:11)"}}'}

I am using same desired capabilities in all the scripts.