unable to find valid certification path to requested target

unable to find valid certification path to requested target

We are getting this error message when we try to update a request with a custom function. We do have ldap in our enviornment and an SSL certificate. We do not have any issues with emails it's just when we try to use this custom function. 

I've looked at these articles but they talk about if you have issues with email which is a little different than our situation. 

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