Update error message for interactive incompatible plugins (#9896)

Co-authored-by: Kaushik B <[email protected]>

Author: awaelchli

CHANGELOG.md

@@ -273,6 +273,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Update the logic to check for accumulation steps with deepspeed ([#9826](https://github.com/PyTorchLightning/pytorch-lightning/pull/9826))
 
 
+- Updated error message for interactive incompatible plugins ([#9896](https://github.com/PyTorchLightning/pytorch-lightning/pull/9896))
+
+
 ### Deprecated
 
 - Deprecated trainer argument `terminate_on_nan` in favour of `detect_anomaly`([#9175](https://github.com/PyTorchLightning/pytorch-lightning/pull/9175))

pytorch_lightning/trainer/connectors/accelerator_connector.py

@@ -845,7 +845,9 @@ def check_interactive_compatibility(self):
             raise MisconfigurationException(
                 f"Selected distributed backend {self._distrib_type} is not compatible with an interactive"
                 " environment. Run your code as a script, or choose one of the compatible backends:"
-                f" {', '.join(DistributedType.interactive_compatible_types())}"
+                f" {', '.join(DistributedType.interactive_compatible_types())}."
+                " In case you are spawning processes yourself, make sure to include the Trainer"
+                " creation inside the worker function."
             )
 
     def check_horovod(self):