The exception UnboundLocalError: local variable 'index' referenced before assignment
happens in Python when you use a global variable in a function that also defines a local version of the same variable.
index = 0 def foo(): if index == 0: print("ZERO") index = 1 foo()
Because index is defined globally as well as inside the foo()
function, Python throws an exception if you try to use the variable inside foo
before it’s declared.
In this case, we want to rename the variable to avoid the conflict.
index = 0 def foo(): if index == 0: print("ZERO") findex = 1 foo()
If you’re looking to get a deeper understanding of how Python application monitoring works, take a look at the following articles:
Get actionable, code-level insights to resolve Python performance bottlenecks and errors.
Create a free Sentry account
Create a Python project and note your DSN
Grab the Sentry Python SDK
pip install --upgrade sentry-sdk
import sentry_sdk sentry_sdk.init( "https://<key>@sentry.io/<project>", # Set traces_sample_rate to 1.0 to capture 100% # of transactions for performance monitoring. # We recommend adjusting this value in production. traces_sample_rate=1.0, )
Loved by over 4 million developers and more than 90,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.