BUG-000173571 for ArcGIS Online

Bug ID Number	BUG-000173571
Submitted	January 13, 2025
Last Modified	June 18, 2025
Applies to	ArcGIS Online
Version found	Nov 2024
Operating System	Windows OS
Operating System Version	11.0 64 bit
Status	As Designed

Additional Information

Curly braces are designated as unsafe characters to include within URLs and must be encoded to be used safely. Otherwise, the values will be sanitized from the URL. Refer to this documentation: https://support.exactonline.com/community/s/knowledge-base#All-All-DNO-Content-urlcharacters for more information. Links containing curly braces can be successfully launched from other places, e.g. the attribute table. This is a bug and will be fixed in the next updates of ArcGIS Online and Enterprise.

Workaround

There are several safe options for generating a URL for pop-ups that include a specific value or have a value change dynamically.

Use the link tool in the text editor to create the link. The link can be static or dynamic, e.g., baseURL + {field_name}. The curly braces in this case are not part of the URL. They are ArcGIS's way of referencing a field or attribute expression so that values from the dataset can be dynamically inserted.
Alternatively, use Arcade to generate the URL, either by using attribute expressions or Arcade elements. For example, return 'baseURL' + $feature.ID, or leverage text functions such as Right() and EncodeURL() to extract and encode the value enclosed in curly braces, then append it to the base URL.