SharePoint Document Issues

Why SharePoint Adds Underscores to Column Names & How to Find Them for APIs

Ayan Masood Oct 14, 2026 870 views

Question details

Users encounter API request errors in SharePoint because the required internal column name contains underscores or encoded characters, even if the visible display name does not.

How to Find SharePoint Internal Column Names with Underscores

Product: Microsoft SharePoint
Device & OS: not provided
Scenario: Making API requests to SharePoint lists or libraries and referencing specific columns.
Observed behavior: The API request fails or requires an internal column name with underscores instead of the visible display name shown on the site.

Before you start

Ensure you have Site Owner or Designer permissions on the SharePoint site to access the List Settings or Library Settings where internal names are exposed.

Solution 1Recommended

Identify the Internal Column Name via List Settings

Locate the exact internal name assigned by SharePoint to use in your API requests to prevent referencing errors.

When a column is created, SharePoint assigns a permanent internal name that is registered in its database. If spaces or special characters were used initially, SharePoint encodes them (e.g., replacing spaces with '_x0020_'). Even if you change the display name later, the internal name remains the same and must be used for all API calls.

Navigate to List Settings

Open your SharePoint list or library, click the Gear icon (Settings) in the top right corner, and select 'List settings' or 'Library settings'.

Select the Target Column

Scroll down the settings page to the 'Columns' section and click on the specific column name you want to query in your API.

Inspect the URL

Look at the URL in your browser's address bar. Find the text at the very end of the URL, immediately following 'Field='.

Copy the Internal Name

Copy this exact string from the URL, including any underscores or encoded characters, and use it as the column reference in your API request.

Identify the Internal Column Name via List Settings

URL Encoding Decoding: If you see '%5F' in the URL, this is the URL-encoded version of an underscore ('_'). Ensure you decode it back to an underscore in your API call script.

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Frequently Asked Questions

Can I change the internal name of a SharePoint column?

No, once a column is created in SharePoint, its internal name becomes permanent and cannot be altered. If you require a different internal name for your API calls, you must delete the existing column and create a new one with the desired name.

Why do I see '_x0020_' in my SharePoint column internal name?

SharePoint uses URL encoding for special characters and spaces when generating internal database names. The sequence '_x0020_' represents a space character that was present when the column was originally created.

How do I avoid underscores and encoded characters in future columns?

To avoid complex internal names, initially create the column without spaces or special characters (e.g., name it 'DocumentTitle'). Once the column is created, edit its settings to change the display name to include spaces (e.g., 'Document Title'). The internal name will remain clean.

Document & File Issues