Bot : 502 Bad Gateway in "test in web chat"

Question

Bot : 502 Bad Gateway in "test in web chat"

Sam 6

Hi,

I published a bot to Azure that was based on the QnA Maker bot (I downloaded the source code, modified it, and re-published it under a different bot name)

Then, testing the bot with the "test in web chat" I get a 502 bad gateway. It does not seem to be a timeout as the error appears instantly

Does someone have experience with a similar problem ?

Thank you

romungi-MSFT 48,906 Reputation points Microsoft Employee Moderator

2021-03-03T10:34:39.013+00:00

@Sam Just curious to check if the publish was successful? If you have changed the name of the bot did you change the app service name to a new one? I think it should retain the same app service settings because bot published from QnAMaker usually use the same name for the Webapp bot along with app service/plan. So, if you have renamed the bot the chances of some settings of app service being overwritten is probable. I would debug the app from the emulator to debug the issue or re-publish with original code to check if app service name change was the issue.

Costales Arias, Felipe Alberto 0

To update the application service
If you have an existing App Service (web app) resource for your bot and the bot is a user-assigned managed identity app, you may need to update the bot's app service:

Go to the App Service blade of the bot web application.
Under Settings, select Identity.
On the Identity sheet, select the User Assigned tab and Add (+).
On the Add user-assigned managed identity blade:
Select your subscription.

Under User-assigned managed identities, select the bot's managed identity. If the managed identity was automatically generated, it will get the same name as the bot.

Select Add to use this identity for the bot.

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romungi-MSFT 48,906 Reputation points Microsoft Employee Moderator

2021-03-03T10:34:39.013+00:00

@Sam Just curious to check if the publish was successful? If you have changed the name of the bot did you change the app service name to a new one? I think it should retain the same app service settings because bot published from QnAMaker usually use the same name for the Webapp bot along with app service/plan. So, if you have renamed the bot the chances of some settings of app service being overwritten is probable. I would debug the app from the emulator to debug the issue or re-publish with original code to check if app service name change was the issue.
Costales Arias, Felipe Alberto 0 Reputation points

2023-11-01T23:13:02.85+00:00

To update the application service If you have an existing App Service (web app) resource for your bot and the bot is a user-assigned managed identity app, you may need to update the bot's app service: Go to the App Service blade of the bot web application. Under Settings, select Identity. On the Identity sheet, select the User Assigned tab and Add (+). On the Add user-assigned managed identity blade: Select your subscription. Under User-assigned managed identities, select the bot's managed identity. If the managed identity was automatically generated, it will get the same name as the bot. Select Add to use this identity for the bot.

Answer 1

HI @romungi-MSFT

Thank you so much for your answer and suggestion. I will share my experience here as it might help others.
The reason the bot channel service was not responding with the 502 Bad Gateway is because the web app was not running at all, it had silently failed to start.

To see that, in the web app service, click on the URL and if it doesn't say something about web sockets, it's probably not running.

Then, I got some help to realize that in the web app service we can actually browse the logs : the app was not starting because there was a file named <somethingjsonresource>.metaproj and basically the fact there is any file other than the *.csproj ending with pro is enough to block the web app from starting (it says there are multiple project files.... !)

So I re-published after renaming this file and now it all works

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Bot : 502 Bad Gateway in "test in web chat"

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