Internal error with a single webhook

Hi all

I’m running n8n on Centos7
n8n 0.76.0
nodejs 10.22.0

Just a single webhook test-url I call locally with curl
Does someone see what is the cause ? Thank you

centos7> n8n
n8n ready on 0.0.0.0, port 5678
Version: 0.76.0

Editor is now accessible via:
http://localhost:5678/

Press "o" to open in Browser.
ERROR RESPONSE
Error: There was a problem executing the workflow.
    at Object.executeWebhook (/usr/lib/node_modules/n8n/dist/src/WebhookHelpers.js:282:30)
    at process._tickCallback (internal/process/next_tick.js:68:7)

centos7> curl -i -X POST -H 'Content-Type: application/json' -d '{ "counter" : 467 }' http://localhost:5678/webhook-test/hook1
HTTP/1.1 500 Internal Server Error
X-Powered-By: Express
Access-Control-Allow-Origin: http://localhost:8080
Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, PATCH, DELETE
Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, sessionid
H2: 47
Content-Type: application/json; charset=utf-8
Content-Length: 286
ETag: W/"11e-FQklKyi3aBW+TKvD/BZ8oz8Qvis"
Vary: Accept-Encoding
Date: Wed, 05 Aug 2020 09:35:06 GMT
Connection: keep-alive

{"code":0,"message":"There was a problem executing the workflow.","stack":"Error: There was a problem executing the workflow.\n    at Object.executeWebhook (/usr/lib/node_modules/n8n/dist/src/WebhookHelpers.js:282:30)\n    at process._tickCallback (internal/process/next_tick.js:68:7)"}centos7>