Magento 1.9.3.9 checkout error "please specify a shipping method"

[Rahul1273]

When i click on place order button in checkout, I'm getting following error
"please specify a shipping method"

I've selected the free shipping method.
I've also tried some hacks in sales quote.php but didn't work. Its something like rates is null.

[burt_joseph]

Hello Rahul1273,

are you using a 3rd party shipping app? 

[TwoHatslogic]

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@burt_joseph wrote:

Hello Rahul1273,

are you using a 3rd party shipping app? 

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No