Tridion Docs: Security Token Exception ID4175

System.IdentityModel.Tokens.SecurityTokenException: ID4175: The issuer of the security token was not recognized by the IssuerNameRegistry. To accept security tokens from this issuer, configure the IssuerNameRegistry to return a valid name for this issuer.

1. Open the new certificate from IIS>Browse to Certification Path>Export the certificate authority certificates.
2. Click on Start>mmc.exe>File>Add/Remove Snap In> Certificates>Trusted Root Authority>Certificates>Right click
3. Import the certificate authority certificates.

2) Reset IIS:

1. Cached sdf file still holding the old cert.
2. Stop all appPools
3. Rename sdf file to sdf.bak
4. Restart appPools.

3) An incorrect server certificate has been used. Make sure that you have entered the correct certificate in the input parameters.

1. Follow the steps in Resolution 1 to see which certificate has been used to encrypt HTTPS traffic
2. Open a command prompt and enter 

3. certutil -store "my"

4. find the certificate that has been used and open the input parameters
5. Search for the ThumbPrint parameter and compare the values
6. If you have a different value, correct the value and reinstall architect

Also see:
Troubleshooting Relying parties and Certificate issues