I can successfully make a patch request to the tooling api to update a custom fields api name. However, if I include any of the field properties in the CustomFieldMetadata object I get an internal salesforce error.

successful request:

PATCH: /services/data/v29.0/tooling/sobjects/CustomFieldDefinition/{ID}
 "DeveloperName" : "NewName"

failed request:

PATCH: /services/data/v29.0/tooling/sobjects/CustomFieldDefinition/{ID}
  "DeveloperName" : "NewName",
  "Metadata" : {"length": 100}

gack ids:

118968544-21444 (-1657627855)

1623052628-129393 (-1657627855)

  • Have you filed a case with salesforce support yet? I'd like to link this issue to the support case if you have one.
    – Ryan Guest
    Commented Oct 22, 2013 at 23:18
  • 1
    @RyanGuest Thanks for reaching out! I went ahead and logged a case (#09822682). Commented Oct 23, 2013 at 16:00
  • hey there, any updates on your cases? I'm trying to build a tool to fetch/update field descriptions which needs this functionality.. Commented Sep 30, 2014 at 19:12
  • @guy No, as far as I know the tooling API still doesn't support this. Commented Sep 30, 2014 at 20:17

2 Answers 2


This is a known issue with the tooling api with no current ETA for the fix. The bug number is W-1904760.

For other people who want to programmatically work with their custom field metadata I would recommend Andrew Fawcett's excellent metadata api wrapper.


Do not have enough reputation points to post this as a comment, so having to post as an "answer".

Just wanted to let you know that you are not alone. It looks like a common problem on SFDC side.

Here is what I get when try to update text field length using SOAP flavour of Tooling API.

    val f = new CustomField
    val md = new CustomFieldMetadata


[ApiFault  exceptionCode='UNKNOWN_EXCEPTION'
exceptionMessage='An unexpected error occurred. Please include this ErrorId if you contact support: 497298247-26206 (803645494)'

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