diff --git a/CHANGELOG.unreleased.md b/CHANGELOG.unreleased.md
index 0c54d57254c..4cd31ff493c 100644
--- a/CHANGELOG.unreleased.md
+++ b/CHANGELOG.unreleased.md
@@ -21,6 +21,7 @@
 
 - [Hub/Recipes/Kubernetes] Properly sort versions in selector
 - [Host/Network] Fix `an error has occurred` briefly displaying in 'Mode' column of the host's Network tab (PR [#7954](https://github.com/vatesfr/xen-orchestra/pull/7954))
+- [REST API] Fix VDI export broken in XO 5.96.0 and not completely fixed in XO 5.98.0
 
 ### Packages to release
 
@@ -41,6 +42,7 @@
 - @xen-orchestra/lite minor
 - @xen-orchestra/web minor
 - @xen-orchestra/web-core minor
+- xo-server patch
 - xo-web minor
 
 <!--packages-end-->
diff --git a/packages/xo-server/src/xo-mixins/rest-api.mjs b/packages/xo-server/src/xo-mixins/rest-api.mjs
index 9daa928a543..dad0dc44cd1 100644
--- a/packages/xo-server/src/xo-mixins/rest-api.mjs
+++ b/packages/xo-server/src/xo-mixins/rest-api.mjs
@@ -955,7 +955,14 @@ export default class RestApi {
         const nbdConcurrency = req.query.nbdConcurrency && parseInt(req.query.nbdConcurrency)
         const stream = await req.xapiObject.$exportContent({ format: req.params.format, preferNbd, nbdConcurrency })
 
-        res.writeHead(200, 'OK', { 'content-disposition': 'attachment', 'content-length': stream.length })
+        const headers = { 'content-disposition': 'attachment' }
+
+        const { length } = stream
+        if (length !== undefined) {
+          headers['content-length'] = length
+        }
+
+        res.writeHead(200, 'OK', headers)
         await pipeline(stream, res)
       })
     )