Blank page for some users

Locos · February 6, 2023, 4:38pm

Hi guys,

Describe the issue/error/question

We’re 3 users using a self hosted docker (through traefik) version of n8n based on the docker image of n8n-python :
https://hub.docker.com/r/naskio/n8n-python

Before I was using your own image, and no problem (but it was small workflows).

Now, sometimes, all of us or 2 of my users are getting a blank page like this :

The weird thing is than, me, I was able to see and navigate, and them, a reload doesn’t work, a cache clear doesn’t work. But if they use private navigation, they can access to it.

It looks than workflow are running well, but users can’t access to the UI. Any idea ?

What is the error message (if any)?

You can see 1 error message in the console of the web browser.
I saw an other error in the docker logs of the n8n app :

This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason:
ReferenceError: AbortSignal is not defined
    at PostHogClient.<anonymous> (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:747:6)
    at step (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:102:23)
    at Object.next (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:83:53)
    at /usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:76:71
    at new Promise (<anonymous>)
    at __awaiter (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:72:12)
    at PostHogClient.PostHogCore.fetchWithRetry (/usr/local/lib/node_modules/n8n/node_modules/posthog-node/lib/index.cjs.js:1285:16)
    at PostHogClient.<anonymous> (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:433:40)
    at step (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:102:23)
    at Object.next (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:83:53)
    at /usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:76:71
    at new Promise (<anonymous>)
    at __awaiter (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:72:12)
    at PostHogClient.PostHogCore._decideAsync (/usr/local/lib/node_modules/n8n/node_modules/posthog-node/lib/index.cjs.js:1003:16)
    at PostHogClient.PostHogCore.decideAsync (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:407:17)
    at PostHogClient.<anonymous> (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:585:24)
    at step (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:102:23)
    at Object.next (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:83:53)
    at /usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:76:71
    at new Promise (<anonymous>)
    at __awaiter (/usr/local/lib/node_modules/n8n/node_modules/node_modules/tslib/tslib.es6.js:72:12)
    at PostHogClient.PostHogCore.reloadFeatureFlagsAsync (/usr/local/lib/node_modules/n8n/node_modules/posthog-node/lib/index.cjs.js:1143:16)
    at PostHogClient.PostHogCore._sendFeatureFlags (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:614:10)
    at PostHogClient.capture (/usr/local/lib/node_modules/n8n/node_modules/posthog-core/src/index.ts:276:12)
    at PostHog.capture (/usr/local/lib/node_modules/n8n/node_modules/posthog-node/src/posthog-node.ts:117:24)
    at /usr/local/lib/node_modules/n8n/src/telemetry/index.ts:193:20
    at new Promise (<anonymous>)
    at Telemetry.track (/usr/local/lib/node_modules/n8n/src/telemetry/index.ts:177:10)
    at InternalHooksClass.onWorkflowSaved (/usr/local/lib/node_modules/n8n/src/InternalHooks.ts:164:19)
Could not initialize license manager sdk

Please share the workflow

Any workflow, any page

Information on your n8n setup

n8n version: 0.213.0
Database you’re using (default: SQLite): default
Running n8n with the execution process [own(default), main]: default
Running n8n via [Docker, npm, n8n.cloud, desktop app]: Docker (n8n-python)

Jon · February 6, 2023, 5:29pm

Hey @Locos,

Can you try reverting to the official image and see if that has the same problem for you?

Locos · February 6, 2023, 6:48pm

Thanks for your time @Jon

I would love to say yes. But that’s used by most of my workflows now. I don’t really want to loose anything.
The image is auto updated based on yours.

Do you have any good ways to debug/retrieve information about any service error ?
I saw some post with the same problem but they got no response.

And the big question is, why I can use n8n, but other users can’t ? Until they try on private navigation

Locos · February 7, 2023, 8:23am

This morning, I tried again. No users can access to the UI (blank page).
For me, I was still able to see the interface but :

not in private navigation (blank page)
in normal navigation after I reload the cache, I can’t no more access to the UI.

It’s looks like the cache have an incidence

Can it come from my apache2 reverse proxy ?
Also when my automatic backup do their job, the server get down for some time. It wasn’t the case before.

When visiting the UI, I got this message in the javascript console : Uncaught SyntaxError: Invalid or unexpected token (at ParameterInputList-7aeef29e.js:53:9682)

Just saw this topic: Python node - #22 by jan
Hope it will help me solve this issue

Jon · February 7, 2023, 10:44am

Hey @Locos,

I suspect the issue is partially down to your proxy although the posthog part is ours but shouldn’t cause an issue.

Are there any ad blockers or VPNs being used? Have you checked the logs on the reverse proxy or tried direct access to see if that works?

I would still be tempted to set up an instance using our docker image to see if the same issue happens there, The image you are using isn’t linked to ours and is instead an NPM install of n8n in a custom container it also doesn’t use the same base image we use.

Locos · February 13, 2023, 9:57am

Hi @Jon,

After checking our workflows, we detected some error inside. After fixing it, the blank page doesn’t appear anymore.

Really weird but maybe caused by community nodes.

Thanks for your help

Jon · February 13, 2023, 10:14am

Hey @Locos,

That is interesting, Which nodes are you using?

Locos · February 13, 2023, 10:30am

Ninox & python :

We solved a python node which has solved the blank page

system · May 14, 2023, 10:30am

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