=== Error ===
Request ID: `INSERT_ID`
The message lacks a normalised form, and embeds JSON-encoded messages within, which makes it a big hard to read, but here it is:
```name=message
[W6FlIgrAEHAAAI3cJhYAAACX] /w/api.php?format=json&formatversion=2&action=jsondata&title=Wynyard+railway+station+marker.map ErrorException from line 309 of /srv/mediawiki/php-1.32.0-wmf.20/includes/debug/MWDebug.php: PHP Warning: API call had warnings trying to get remote JsonConfig: warnings={"main":{"*":"Subscribe to the mediawiki-api-announce mailing list at \u003Chttps://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce\u003E for notice of API deprecations and breaking changes. Use [[Special:ApiFeatureUsage]] to see usage of deprecated features by your application."},"revisions":{"*":"Because \"rvslots\" was not specified, a legacy format has been used for the output. This format is deprecated, and in the future the new format will always be used."}}, query={"action":"query","titles":"Data:Wynyard railway station marker.map","prop":"revisions","rvprop":"content","continue":""} [Called from JsonConfig\JCUtils::warn in /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCUtils.php at line 53]
```
```name=stacktrace,lines=10
#0 /srv/mediawiki/php-1.32.0-wmf.20/includes/debug/MWDebug.php(309): MWExceptionHandler::handleError(integer, string, string, integer, array, array)
#1 /srv/mediawiki/php-1.32.0-wmf.20/includes/debug/MWDebug.php(164): MWDebug::sendMessage(string, array, string, integer)
#2 /srv/mediawiki/php-1.32.0-wmf.20/includes/GlobalFunctions.php(1147): MWDebug::warning(string, integer, integer, string)
#3 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCUtils.php(53): wfLogWarning(string)
#4 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCUtils.php(125): JsonConfig\JCUtils::warn(string, array, array)
#5 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCCache.php(221): JsonConfig\JCUtils::callApi(CurlHttpRequest, array, string)
#6 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCCache.php(183): JsonConfig\JCCache->getPageFromApi(string, CurlHttpRequest, array)
#7 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCCache.php(60): JsonConfig\JCCache->loadRemote()
#8 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCSingleton.php(373): JsonConfig\JCCache->get()
#9 /srv/mediawiki/php-1.32.0-wmf.20/extensions/JsonConfig/includes/JCDataApi.php(20): JsonConfig\JCSingleton::getContent(JsonConfig\JCTitle)
#10 /srv/mediawiki/php-1.32.0-wmf.20/includes/api/ApiMain.php(1587): JsonConfig\JCDataApi->execute()
#11 /srv/mediawiki/php-1.32.0-wmf.20/includes/api/ApiMain.php(531): ApiMain->executeAction()
#12 /srv/mediawiki/php-1.32.0-wmf.20/includes/api/ApiMain.php(502): ApiMain->executeActionWithErrorHandling()
#13 /srv/mediawiki/php-1.32.0-wmf.20/api.php(87): ApiMain->execute()
```
== Notes ===
Found via `channel:error AND message:JCUtils`. First reported on 1.32.0-wmf.16 (possibly earlier).
Apparently comes when using `action=jsondata`. The API yields:
```counterexample
"revisions":{
"*":"Because \"rvslots\" was not specified, a legacy format has been used for the output. This format is deprecated, and in the future the new format will always be used."}
```
Previously mentioned at T202764#4537363.