Merge pull request #294521 from KendalBond007/FHIRTroubleshootUpdate_12Feb25

Update convert-data-troubleshoot.md

Author: prmerger-automator[bot]

articles/healthcare-apis/fhir/convert-data-troubleshoot.md

@@ -5,7 +5,7 @@ services: healthcare-apis
 author: msjasteppe
 ms.service: azure-health-data-services
 ms.topic: troubleshooting
-ms.date: 08/28/2023
+ms.date: 02/12/2025
 ms.author: jasteppe
 ---
 
@@ -29,6 +29,10 @@ The `$convert-data` operation applies post processing logic after the template i
 ## Message size
 There isn’t a hard limit on the size of the messages allowed for the `$convert-data` operation. However, for content with a request size greater than 10 MB, server errors `500` are possible. If you're receiving `500` server errors, ensure your requests are under 10 MB.
 
+## Template size and complexity
+
+If you receive `504 Gateway Timeout` errors, it may be the result of template processing time. Updating templates to reduce loops and iterations can greatly increase performance. Consider retrying your request with a smaller or simpler template. 
+
 ## Why are my dates being converted when transforming JSON data?
 
 It's possible for dates supplied within JSON data to be returned in a different format than what was supplied. During deserialization of the JSON payload, strings that are identified as dates get converted into .NET DateTime objects. These objects then get converted back to strings before going through the Liquid template engine. This conversion can cause the date value to be reformatted, and represented in the local timezone of the FHIR service.