The workspace contains some nodes that are not properly configured

General
5

Can you find any sign of it in your flow.json file? (in node red home directory or in projects if you are using projects) Maybe it is somehow corrupted but so lightly that everything else can still work properly.

normally the entry looks like this

{
      "id":"66bc4166.8786c",
      "type":"mqtt in",
      "z":"3c409e2.49e6162",
      "name":"",
      "topic":"mqtttopic/#",
      "qos":"2",
      "datatype":"auto",
      "broker":"6f39007a.acb4d",
      "x":220,
      "y":270,
      "wires":[
         [
            "82baddd8.27185"
         ]
      ]
   }