Occasional 403 error on IIS

kneidels

7/18/24, 2:15 PM

Using IIS 10 on Windows Server 2019. I am not a server admin, I am a developer who manages sites on the rented server.

I have a report that runs through names, and via a client side scripts, access an ajax file to check if the person's status is valid. So, when the page loads, ~100 ajax calls could be run. On some servers, this report seems to complete perfectly (with 100 names checked), but on the current server - after a few successful calls, the rest (like 90% of them) are rejects with a generic 403 error - 403 Forbidden.

When I run each of these individual links manually - they load perfectly. Maybe its some kind of a traffic block - when a high number (100) of requests to the same file (with different parameters) are sent - that some are blocked? Where would I be able to check this?

Not sure if this is related, but on the odd case it might be - I'll mention it: on Chrome, sometimes all css/js files linked in the header of the site, are rejected with the same 403 error. Which obviously messes the site. on Firefox, there is no similar issue, even the same exact pages.

Thanks

UPDATE: Uploading what seems to come up in the Trace. the substatus of 501 does not seem very telling?

1 + 4

http-status-code-403

iis-10

windows-server-2019

Lex Li

7/18/24, 2:43 PM

Try to learn how to manage IIS and troubleshoot common issues like that. FRT is usually the start, https://learn.microsoft.com/en-us/troubleshoot/developer/webapps/iis/health-diagnostic-performance/troubleshoot-php-with-failed-request-tracing

kneidels

7/18/24, 3:03 PM

Thank you @LexLi - I have updated the question with what came up in the FRT.

Lex Li

7/18/24, 10:38 PM

https://learn.microsoft.com/en-US/troubleshoot/developer/webapps/iis/www-administration-management/http-status-code You can learn about 403.501 from here.

kneidels

7/19/24, 8:35 AM

@LexLi thank you. If you would like to submit as an answer, I will accept, along with solution options found at: https://www.itnota.com/solving-intermittent-403-501-error-iis/

Score:0

Server

kneidels

7/23/24, 11:21 AM

With thanks to @LexLi Error code/substatus details at: https://learn.microsoft.com/en-US/troubleshoot/developer/webapps/iis/www-administration-management/http-status-code

And solution found here: https://www.itnota.com/solving-intermittent-403-501-error-iis/

+ 0

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