module 'tensorflow' has no attribute 'placeholder'

This error message typically occurs when you are using an older version of TensorFlow that does not support the `placeholder` function.

In TensorFlow 2.0 and later versions, the `placeholder` function has been replaced by the `tf.keras.Input` function. You can use this function to define a placeholder for your input data.

If you are using an older version of TensorFlow, you can try upgrading to the latest version or using a different function to define your placeholders.

For example, in TensorFlow 1.x, you can define a placeholder using the following code:

import tensorflow as tf

# Define a placeholder for input data
x = tf.placeholder(tf.float32, shape=(None, 784))

In TensorFlow 2.0 and later versions, you can define a placeholder using the following code:

import tensorflow as tf

# Define a placeholder for input data
x = tf.keras.Input(shape=(784,))