Hello Fabio,
What is the exact js error message? Is it possible to show your codes here? I have tried to test AutoComplete Extender with some simple javascript, but it works fine. To give future investigation on this, we need to reproduce the issue in our side firstly. So, if you can simplify the project and share a reproduciable one, it will be helpful.
By the way, are you MSFT since your signature ends with "-Microsoft". :-)
Have a nice day!
Ji Zhou
MSDN Subscriber Support in Forum
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