'Gray color output in folium choropleth

Hi I am new in Data Analytics, I have a problem with folium choropleth map, the color scale is not working in my map, it is showing gray color only.

Solution 1:^[1]

Here is the error:

Key_on='feature.properties.?UNICIPALI',

Modify it as:

key_on='feature.properties.?UNICIPALI',

if that doesn't work, you should paste your code and dataset here

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Solution	Source
Solution 1	paulyang0125