We have an integration in a sandbox environment that uses the SF session ID. In classic we get a valid session ID but when we switch to lightning, we get a session ID, however that ID is not valid. We're trying to understand why this is so and what we can do to get valid IDs from either environment.

e.g. Where the first ID is returned for classic and the second for lightning. The second is not valid. 

http://XXXXXXXXXX/sforce_login?sid={!$Api.Session_ID}&instance={!$Api.Enterprise_Server_URL_480}&cid={!Contact.Id}"

Session ID: 00Dg0000006VWjo!ARAAQL3rmIE7Jp_uaZi9CIcIN4oXu5py50ypG3kIKeNu4ySza37EoZ4HNv4Qn9jLPsiqc1QvjGxtmLw.xOFT_QMVAjnWFfYk
Session ID: 00Dg0000006VWjo!ARAAQItccgmw5iPsBjBtfTgYrSyF9CCQOtBKIg4dSWvqQPJBI89J5doGqdXqcJ20lphEAWQhqYHV_vhYOuJxWR40pYtJTqPd

We have an integration in a sandbox environment that uses the SF session ID. In classic we get a valid session ID but when we switch to lightning, we get a session ID, however that ID is not valid. We're trying to understand why this is so and what we can do to get valid IDs from either environment.

e.g. Where the first ID is returned for classic and the second for lightning. The second is not valid. 

http://XXXXXXXXXX/sforce_login?sid={!$Api.Session_ID}&instance={!$Api.Enterprise_Server_URL_480}&cid={!Contact.Id}"

Session ID: 00Dg0000006VWjo!ARAAQL3rmIE7Jp_uaZi9CIcIN4oXu5py50ypG3kIKeNu4ySza37EoZ4HNv4Qn9jLPsiqc1QvjGxtmLw.xOFT_QMVAjnWFfYk
Session ID: 00Dg0000006VWjo!ARAAQItccgmw5iPsBjBtfTgYrSyF9CCQOtBKIg4dSWvqQPJBI89J5doGqdXqcJ20lphEAWQhqYHV_vhYOuJxWR40pYtJTqPd