Unable to create domain in Plesk: mailmng failed: Incorrect Content-Type: must be textual to extract_string, JSON to extract_json. at generateDKIMKeyPair(default, 2048)(SmarterMail::Common::Domain::generateDKIMKeyPair line 199)

Symptoms

• Unable to create domain in Plesk, the process fails with the following error message:
  

  CONFIG_TEXT: mailmng failed: Incorrect Content-Type: must be textual to extract_string, JSON to extract_json.
  at generateDKIMKeyPair(default, 2048)(SmarterMail::Common::Domain::generateDKIMKeyPair line 199)
  at Unable to execute console command: '--generate-domain-dkim-key-pair'(vconsoleapp::start line 95)
  at Unable to execute command: '"C:\Program Files (x86)\Plesk\admin\bin\mailmng" --generate-domain-dkim-key-pair "--domain-name=example.com" "--key-size=2048" "--selector=default"'(vconsoleapp::run line 117)

• Plesk is integrated with the Remote SmarterMail Server

Cause

The versions of the Remote SmarterMail Server is oudated, for example 100.0.7544 which was released on 27.08.2020

Resolution

1. Upgrade Remote SmarterMail to the latest available version

2. Go to Plesk > Tools & Settings > Server Components

3. Press the Refresh button

4. Then try again to create a domain in Plesk