values passed to the '_id' (mongodb) is not a valid ObjectId Pymongo

I have a python script that receive (from a node.js script) an _id for a mongodb document as an argument.Using that value I'm trying to query the db and retrieve a document.

However, when i try to run the script it throws an error saying "'xxxxxxxxxx'is not a valid ObjectId, it must be a 12-byte input or a 24-character hex string".

my script where the error is causing: result = db.req.find_one({"_id": ObjectId(sys.argv[1])})

When i check the type() of the sys.argv[1] it says string. I thought wrapping the string around ObjectId should do the trick.

Anyone one know whats the reason causing the issue?

Thanks in advance..

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