https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613388#M87124 <P>Hi Noah,</P><P>I tried different attachments and the same error happens. The mapping is part of a bigger application.&nbsp; Originally, it was .net framework MVC and the code was working fine. Recently, we upgraded to .net core 8 and the same code fails.</P> Fri, 09 May 2025 18:48:21 GMT MKY 2025-05-09T18:48:21Z https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613228#M87119 <P>I have a popup trigger "Add Attachment". It invokes a function to dynamically create a form and select an attachment.</P><P>It returns an error :</P><P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="MKY_0-1746798310501.png" style="width: 400px;"><img src="https://community.esri.com/t5/image/serverpage/image-id/131869iF2707B70FDE41F86/image-size/medium?v=v2&amp;px=400" role="button" title="MKY_0-1746798310501.png" alt="MKY_0-1746798310501.png" /></span></P><P>The function addAttachment</P><LI-CODE lang="javascript">function addAttachment(feature) { //create form const attachmentForm = document.createElement("form"); attachmentForm.setAttribute("id", "addAttachmentForm"); let fileSelector = document.createElement("input"); fileSelector.setAttribute("id", "fileSelector"); fileSelector.setAttribute("type", "file"); fileSelector.setAttribute("name", "attachment"); let entInput = document.createElement("input"); entInput.setAttribute("type", "hidden"); entInput.setAttribute("name", "f"); entInput.setAttribute("value", "json"); attachmentForm.appendChild(fileSelector); attachmentForm.appendChild(entInput); document.getElementById("resource-container").appendChild(attachmentForm); document.getElementById("fileSelector").addEventListener("change", (e) =&gt; { let selectedFiles = (e.target as any).files; let layer = feature.layer; layer.addAttachment(feature, attachmentForm).then((result) =&gt; { console.log("attachment added. If successful it will return the objectID of the feature ", result); } }).catch((error) =&gt; { console.log("attachment adding failed: ", error); }); document.getElementById("fileSelector").click(); }</LI-CODE><P>&nbsp;</P><P>Any help is appreciated</P> Fri, 09 May 2025 13:54:47 GMT https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613228#M87119 MKY 2025-05-09T13:54:47Z https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613273#M87121 <P>Looks like the attachment may be invalid? I would try several different attachment and/or attachment types.</P> Fri, 09 May 2025 15:36:46 GMT https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613273#M87121 Noah-Sager 2025-05-09T15:36:46Z https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613388#M87124 <P>Hi Noah,</P><P>I tried different attachments and the same error happens. The mapping is part of a bigger application.&nbsp; Originally, it was .net framework MVC and the code was working fine. Recently, we upgraded to .net core 8 and the same code fails.</P> Fri, 09 May 2025 18:48:21 GMT https://community.esri.com/t5/arcgis-javascript-maps-sdk-questions/featurelayer-addattachments-returns-error/m-p/1613388#M87124 MKY 2025-05-09T18:48:21Z