Fixing UnboundLocalError in Python 3

How to Solve the “Local Variable Referenced Before Assignment” Error

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If you’ve ever gotten the “UnboundLocalError: local variable referenced before assignment” error in Python 3, then this post is for you.

This error can be caused by a number of things, but most often it’s simply because you’re trying to use a variable before it has been assigned a value.

Don’t worry, though, it’s an easy error to fix. In this post, we’ll take a look at what causes this error and how to solve it.

What Causes the UnboundLocalError in Python 3

There are a few different things that can cause the “UnboundLocalError: local variable referenced before assignment” error in Python 3.

The most common cause is simply trying to use a variable before it has been assigned a value. For example, consider the following code:

x = 10

y = x + 1

print(y) # Prints 11

z = y + 1 # Causes an error!

In this code, we first assign the value 10 to the x variable. Then we add 1 to x and store the result in y. Finally, we try to add 1 to y and store the result in z. However, this causes an error because at the time we try to use z, it hasn’t been assigned a value yet.

How to Solve the UnboundLocalError in Python 3

There are a few different ways to solve the “UnboundLocalError: local variable referenced before assignment” error in Python 3.

The most common way is simply to make sure that you assign a value to the variable before you try to use it. For example, consider the following code:

x = 10

y = x + 1 # This line doesn’t cause an error anymore because we’ve assigned a value to y first.

print(y) # Prints 11

z = y + 1 # This line also doesn’t cause an error because z has been assigned a value (12).

In conclusion, the “UnboundLocalError: local variable referenced before assignment” error in Python 3 is caused by trying to use a variable before it has been assigned a value. This error can be easily fixed by simply assigning a value to the variable before using it.