[Bug] Node with multiple Inputs can not be executed "Step by Step"

Questions
#1

Hello,

I don’t know if this is the right place to post, but I found some odd behaviour.

I have a workflow that calls a paged API endpoint.
The response is a token for the next page + message payload.

The setup and error is the same as in the following example:

{
  "nodes": [
    {
      "parameters": {},
      "name": "Start",
      "type": "n8n-nodes-base.start",
      "typeVersion": 1,
      "position": [
        250,
        300
      ]
    },
    {
      "parameters": {
        "conditions": {
          "string": [],
          "number": [
            {
              "value1": "={{$json[\"nextPageToken\"]}}",
              "operation": "smallerEqual",
              "value2": 5
            }
          ]
        }
      },
      "name": "IF",
      "type": "n8n-nodes-base.if",
      "typeVersion": 1,
      "position": [
        650,
        0
      ]
    },
    {
      "parameters": {
        "values": {
          "string": [
            {
              "name": "nextPageToken",
              "value": "1"
            }
          ]
        },
        "options": {}
      },
      "name": "Initialize",
      "type": "n8n-nodes-base.set",
      "typeVersion": 1,
      "position": [
        460,
        290
      ]
    },
    {
      "parameters": {
        "keepOnlySet": true,
        "values": {
          "string": [
            {
              "name": "nextPageToken",
              "value": "={{parseInt($json[\"nextPageToken\"])+ 1}}"
            }
          ]
        },
        "options": {}
      },
      "name": "Call API",
      "type": "n8n-nodes-base.set",
      "typeVersion": 1,
      "position": [
        660,
        290
      ]
    },
    {
      "parameters": {},
      "name": "Do Stuff With Response",
      "type": "n8n-nodes-base.noOp",
      "typeVersion": 1,
      "position": [
        860,
        290
      ]
    },
    {
      "parameters": {},
      "name": "Finished",
      "type": "n8n-nodes-base.noOp",
      "typeVersion": 1,
      "position": [
        850,
        0
      ]
    }
  ],
  "connections": {
    "Start": {
      "main": [
        [
          {
            "node": "Initialize",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "IF": {
      "main": [
        [
          {
            "node": "Call API",
            "type": "main",
            "index": 0
          }
        ],
        [
          {
            "node": "Finished",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Initialize": {
      "main": [
        [
          {
            "node": "Call API",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Call API": {
      "main": [
        [
          {
            "node": "Do Stuff With Response",
            "type": "main",
            "index": 0
          },
          {
            "node": "IF",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  }
}

The normal execution works fine, but I can’t step through it one node at a time.
I get the following Error:
image

If I want step through to change something in the workflow I always have to remove the connection from “If” back to “Call Api”.

Thanks for building such an awesome tool.
Feel free to ask any clarifying question or suggest a better way of handling my use-case.

#2

Is there anything I can add/change to step through the workflow?

#3

@Sopor10 welcome to the community.

Just tested it and I was able to replicate it. Will have a look at it and come back to you. Thanks for letting us know.

#4

Issues with executing workflows manually are sadly expected. Especially if there are loops and other complicated constructs involved as the workflow actually has to first run backward (to figure out what nodes to execute) and then again forward.

It is for sure a bug that we should fix at some point but probably nothing I would honestly prioritize right now. Is something that is probably hard to fix and the chance that we destroy more than what we repair is quite high. We will however address that in the future as we rewrite part of that code in the future.

But that issues will not have any impact on the workflow executing correctly in production. It is currently “only” a limitation for testing it when executing nodes manually.

1 Like
#5

Thanks for your response.

I can live with that Bug, especially as it doesn’t affect the production runs.
If it’s complicated and/or risky to fix, i would probably prefer more awesome new Features beeing build instead :wink:

Thanks again for this nice Plattform

#6

Thanks, that is great to hear!

As written above do we still want to fix it at some point but we also have to prioritize as there is just a limited amount of resources.

Have fun!

1 Like