Server crashes with error Callback failed: the server did not respond

Dash Python
1

I’m still new to Dash, and your help would be greatly appreciated! The server automatically crashes, and I can’t figure out why.

There were no other errors output from my app and my callbacks work fine.

The only error message is the following:

Callback failed: the server did not respond.
(This error originated from the built-in JavaScript code that runs Dash apps. Click to see the full stack trace or open your browser’s console.)
Error: Callback failed: the server did not respond.

at http://127.0.0.1/_dash-component-suites/dash_renderer/dash_renderer.v1_9_1m1617985068.dev.js:93428:11

Sometimes the app crashes as soon as I open the app and nothing is viewable apart from empty components, sometimes the app crashes after the default page is rendered, sometimes the app crashes after I select another item in the dropdown.

Has anyone encountered the same problem and know how to fix this?

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I’ve already looked at Callback failed: the server did not respond - Browser keeps updating and Callback Error when the app is started - #3 by Eduardo, but I’ve had no luck.

2

Hi,

Could you share with us the server logs as well?

3

I wasn’t sure how to get the server log since I’m still new. I was hosting the app on local host and this is the command prompt output after I set dev_tools_silence_routes_logging = False. Let me know if this is what you’re referring to!

T /_reload-hash HTTP/1.1" 200 -
127.0.0.1 - - [06/Jan/2022 23:15:29] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:32] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:33] “GET / HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-layout HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-dependencies HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_favicon.ico?v=1.20.0 HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-component-suites/dash_table/async-highlight.js HTTT /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:29] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:32] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:33] “GET / HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-layout HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-dependencies HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_favicon.ico?v=1.20.0 HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-component-suites/dash_table/async-highlight.js HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-component-suites/dash_table/async-table.js HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:35] “POST /_dash-update-component HTTP/1.1” 500 -
127.0.0.1 - - [06/Jan/2022 23:15:39] “GET /_reload-hash HTTP/1.1” 200 -P/1.1" 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “GET /_dash-component-suites/dash_table/async-table.js HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:34] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [06/Jan/2022 23:15:35] “POST /_dash-update-component HTTP/1.1” 500 -
127.0.0.1 - - [06/Jan/2022 23:15:39] “GET /_reload-hash HTTP/1.1” 200 -

4

Yes, that’s it! Can you run it with debug=True?

5

Great, the previous message I posted was already with debug=True set.
But the following Error: No active result set appears occasionally as well, though not always.
There’s also these two errors sometimes, ERROR: Error! Unsupported type identifier for column @ UNKNOWN TYPE (precision 0, scale 0))
ERROR: ‘NoneType’ object has no attribute ‘get_row_count’

I’m only confused because the app works fine sometimes but the entire app crashes the other times when I didn’t change any of my code.

127.0.0.1 - - [07/Jan/2022 10:05:30] “POST /_dash-update-component HTTP/1.1” 200 -
ERROR: No active result set
127.0.0.1 - - [07/Jan/2022 10:05:31] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:31] “POST /_dash-update-component HTTP/1.1” 500 -
127.0.0.1 - - [07/Jan/2022 10:05:32] “POST /_dash-update-component HTTP/1.1” 500 -
127.0.0.1 - - [07/Jan/2022 10:05:32] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:32] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:32] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:35] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:38] “GET /_reload-hash HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:41] “GET /_reload-hash HTTP/1.1” 200 -
ERROR: No active result set
127.0.0.1 - - [07/Jan/2022 10:05:42] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:42] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:42] “POST /_dash-update-component HTTP/1.1” 500 -
127.0.0.1 - - [07/Jan/2022 10:05:43] “POST /_dash-update-component HTTP/1.1” 200 -
127.0.0.1 - - [07/Jan/2022 10:05:46] “GET /_reload-hash HTTP/1.1” 200 -

6

Hello, I have been facing the same issue. However my app doesnt crash and all the components work as intended. But the message:

Callback failed: the server did not respond.
keeps popping up on starting app.
I even set prevent_initial_callbacks = True and debug= True. To avoid repeated reloading, i have set use_reloader=False

Any help would be appreciated, thanks!