Contract_verification gives internal server error

I have a newly-installed bs instance working reasonably well on my private network, except for one problem.

I want to verify a contract so that I can properly see its details. Following your instructions, I do these steps

  • click on the contract address
  • click on the “code” tab
  • click on “Verify and Publish”

That gives me an “internal server error” on

How can we fix this?