For information on how to check and import certificates, please see the following article here.
Name: Thawte Primary Root CA
Serial Number: 34 4e d5 57 20 d5 ed ec 49 f4 2f ce 37 db 2b 6d
Thumbprint: 91 C6 D6 EE 3E 8A C8 63 84 E5 48 C2 99 29 5C 75 6C 81 7B 81
Download From: https://www.thawte.com/roots/
Notes: This root certificate is required.
Name: Thawte Premium Server CA
Notes: This is a retired CA but is needed for some legacy setups. If you are still having issues with the new root (Thawte Primary Root CA), please try this root. Please contact email@example.com to request this certificate if required.