The “NTC 100K beta 3950” temperature sensor is deprecated and will be removed in the near future.
In order to solve the problem search in your config for sensor_type: NTC 100K beta 3950 and replace it with sensor_type: Generic 3950.
Most users will find the “Generic 3950” temperature sensor more accurate. Anyway you can continue to use the older (typically less accurate) definition. Therefor define a custom thermistor with temperature1: 25, resistance1: 100000, and beta: 3950.