Issue with workflows not running after upgrading to 1.11.11

After upgrading from 1.10.1 to 1.11.1, my workflow encountered errors and failed to run, forcing me to downgrade back to 1.10.

Below is the error message:

{
“error_message”: "1 validation error for VariableMessage\n Value error, Only basic types and lists are allowed. [type=value_error, input_value={‘variable_name’: 'tail_i…: None, ‘stream’: False}, input_type=dict]\n For further information visit Redirecting... ",
“error_type”: “WorkflowNodeError”
}

The node is a workflow TOOL. I checked the TOOL’s execution logs, which appeared normal; the error occurs in the higher-level workflow.

Could you please help identify the issue?