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Web API: Attribute Update Returns 204, but the attribute is not updated

Question asked by MPearson79 on May 4, 2018
Latest reply on May 16, 2018 by MPearson79

Utilizing a web application in IE 11, we have been able to update PI AF Attribute values via the PI Web API for the past couple of weeks until today.


As described in the question: the 204 status code indicates a successful (PUT) operation, but the attribute value in AF is not updating.  GET operations are working as expected.


I have since:

  • Restarted my client machine
  • Restarted the AF server, which also hosts my Web API
  • Reviewed permissions, even given World read/write and read/write data privileges
  • Enabled debug logging and there are no obvious indications of an issue there
  • Ran Web API account with both default and a custom domain service account


Windows Event Log Output:


[PIWebAPI] {6066c9dc-7ebd-4f21-90aa-bb2bc8bf52ef}: Request executing as <domain>\<user>.


Origin: https://localhost:4321

DNT: 1

Cache-Control: no-cache

Connection: Keep-Alive

Accept: application/json, text/javascript, text/plain

Accept-Encoding: gzip, deflate

Accept-Language: en-US

Authorization: Negotiate [Redacted]

Host: <webapihost>

Referer: https://localhost:4321/temp/workbench.html

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko



[PIWebAPI] {6066c9dc-7ebd-4f21-90aa-bb2bc8bf52ef}: Request served.

Access-Control-Allow-Origin: https://localhost:4321

Access-Control-Allow-Credentials: true

Access-Control-Expose-Headers: Allow,Content-Encoding,Content-Length,Date,Location


What am I missing?


Message was edited by: Matthew Pearson;  Added event log data