6 files declare their use of Error in JSON-RPC 8

AddPermissionToRole.php in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/AddPermissionToRole.php

EntityParameterFactory.php in src/ParameterFactory/EntityParameterFactory.php

Handler.php in src/Handler.php

JsonRpcException.php in src/Exception/JsonRpcException.php

Plugins.php in modules/jsonrpc_core/src/Plugin/jsonrpc/Method/Plugins.php

RpcRequestFactory.php in src/Shaper/RpcRequestFactory.php