SSL certificate error - Unable to validate certificate

[David Woolley]

On 23/05/17 23:12, Frank Bratman wrote:
> Can you please help me. I have used this app for years and now a
> problem. I have accepted it many times.

It looks to me as though you have failed to keep your root certificates 
up to date (quite possibly an OS level thing) and gmail has started 
using newer one.  Using View Certificate may give a better clue.