Failed to refresh access token(internal_failure)

Hi, Can someone from the AdWords team please help with resolving this issue "Failed to refresh access token \"error\" : \"internal_failure" How frequent token will expire, i am using only one Adwords account, after some time i am getting error like "Failed to refresh access token \"error\" :

redirect_uri_mismatch in google adwords

Hi Trying to access Google Adword API I am following below steps and failing @step 5 and giving error like* (400.* That’s an error.* Error: redirect_uri_mismatch)* 1. Request a developer token