diff --git a/@xen-orchestra/backups/RemoteAdapter.js b/@xen-orchestra/backups/RemoteAdapter.js
index 9d5e67919aa..f2d9f5a64a2 100644
--- a/@xen-orchestra/backups/RemoteAdapter.js
+++ b/@xen-orchestra/backups/RemoteAdapter.js
@@ -277,6 +277,12 @@ class RemoteAdapter {
       delta !== undefined && this.deleteDeltaVmBackups(delta),
       full !== undefined && this.deleteFullVmBackups(full),
     ])
+
+    const dirs = new Set(files.map(file => dirname(file)))
+    for (const dir of dirs) {
+      // don't merge in main process, unused VHDs will be merged in the next backup run
+      await this.cleanVm(dir, { remove: true, onLog: warn })
+    }
   }
 
   #getCompressionType() {
diff --git a/@xen-orchestra/fs/src/s3.js b/@xen-orchestra/fs/src/s3.js
index 30dde87bbfe..a97fd521177 100644
--- a/@xen-orchestra/fs/src/s3.js
+++ b/@xen-orchestra/fs/src/s3.js
@@ -195,7 +195,7 @@ export default class S3Handler extends RemoteHandlerAbstract {
       Delimiter: '/', // will only return path until delimiters
     })
 
-    if (result.isTruncated) {
+    if (result.IsTruncated) {
       const error = new Error('more than 1000 objects, unsupported in this implementation')
       error.dir = dir
       throw error
@@ -285,7 +285,7 @@ export default class S3Handler extends RemoteHandlerAbstract {
         Prefix: this._dir + path + '/',
         ContinuationToken: NextContinuationToken,
       })
-      NextContinuationToken = result.isTruncated ? result.NextContinuationToken : undefined
+      NextContinuationToken = result.IsTruncated ? result.NextContinuationToken : undefined
       await asyncEach(
         result.Contents,
         async ({ Key }) => {
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecd87713c84..1af6af64421 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,7 +23,7 @@
 ### Bug fixes
 
 - [Dashboard/Health] Fix `error has occured` when a pool has no default SR
-- [Delta Backup] Fix unnecessary full backup when not using S3 [Forum #5371](https://xcp-ng.org/forum/topic/5371/delta-backup-changes-in-5-66)d (PR [#6070](https://github.com/vatesfr/xen-orchestra/pull/6070))
+- [Delta Backup] Fix unnecessary full backup when not using S3 [Forum#5371](https://xcp-ng.org/forum/topic/5371/delta-backup-changes-in-5-66) (PR [#6070](https://github.com/vatesfr/xen-orchestra/pull/6070))
 - [Backup] Fix incorrect warnings `incorrect size [...] instead of undefined`
 
 ### Released packages
@@ -47,8 +47,8 @@
 ### Bug fixes
 
 - [Tables/actions] Fix collapsed actions being clickable despite being disabled (PR [#6023](https://github.com/vatesfr/xen-orchestra/pull/6023))
-- [Backup] Remove incorrect size warning following a merge [Forum #5727](https://xcp-ng.org/forum/topic/4769/warnings-showing-in-system-logs-following-each-backup-job/4) (PR [#6010](https://github.com/vatesfr/xen-orchestra/pull/6010))
-- [Delta Backup] Preserve UEFI boot parameters [#6054](https://github.com/vatesfr/xen-orchestra/issues/6054) [Forum #5319](https://xcp-ng.org/forum/topic/5319/bug-uefi-boot-parameters-not-preserved-with-delta-backups)
+- [Backup] Remove incorrect size warning following a merge [Forum#5727](https://xcp-ng.org/forum/topic/4769/warnings-showing-in-system-logs-following-each-backup-job/4) (PR [#6010](https://github.com/vatesfr/xen-orchestra/pull/6010))
+- [Delta Backup] Preserve UEFI boot parameters [#6054](https://github.com/vatesfr/xen-orchestra/issues/6054) [Forum#5319](https://xcp-ng.org/forum/topic/5319/bug-uefi-boot-parameters-not-preserved-with-delta-backups)
 
 ### Released packages
 
@@ -83,9 +83,9 @@
 
 ### Bug fixes
 
-- [Backup] Fix `handler.rmTree` is not a function (Forum [5256](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it/29) PR [#6041](https://github.com/vatesfr/xen-orchestra/pull/6041) )
-- [Backup] Fix `EEXIST` in logs when multiple merge tasks are created at the same time ([Forum #5301](https://xcp-ng.org/forum/topic/5301/warnings-errors-in-journalctl))
-- [Backup] Fix missing backup on restore (Forum [5256](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it/29) (PR [#6048](https://github.com/vatesfr/xen-orchestra/pull/6048))
+- [Backup] Fix `handler.rmTree` is not a function [Forum#5256](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it/29) (PR [#6041](https://github.com/vatesfr/xen-orchestra/pull/6041))
+- [Backup] Fix `EEXIST` in logs when multiple merge tasks are created at the same time [Forum#5301](https://xcp-ng.org/forum/topic/5301/warnings-errors-in-journalctl)
+- [Backup] Fix missing backup on restore [Forum#5256](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it/29) (PR [#6048](https://github.com/vatesfr/xen-orchestra/pull/6048))
 
 ### Released packages
 
@@ -99,10 +99,10 @@
 
 ### Bug fixes
 
-- [Delta Backup Restoration] Fix assertion error [Forum #5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/16)
-- [Delta Backup Restoration] `TypeError: this disposable has already been disposed` [Forum #5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/20)
-- [Backups] Fix: `Error: Chaining alias is forbidden xo-vm-backups/..alias.vhd to xo-vm-backups/....alias.vhd` when backuping a file to s3 [Forum #5226](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it)
-- [Delta Backup Restoration] `VDI_IO_ERROR(Device I/O errors)` [Forum #5727](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/4) (PR [#6031](https://github.com/vatesfr/xen-orchestra/pull/6031))
+- [Delta Backup Restoration] Fix assertion error [Forum#5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/16)
+- [Delta Backup Restoration] `TypeError: this disposable has already been disposed` [Forum#5257](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/20)
+- [Backups] Fix: `Error: Chaining alias is forbidden xo-vm-backups/..alias.vhd to xo-vm-backups/....alias.vhd` when backuping a file to s3 [Forum#5226](https://xcp-ng.org/forum/topic/5256/s3-backup-try-it)
+- [Delta Backup Restoration] `VDI_IO_ERROR(Device I/O errors)` [Forum#5727](https://xcp-ng.org/forum/topic/5257/problems-building-from-source/4) (PR [#6031](https://github.com/vatesfr/xen-orchestra/pull/6031))
 - [Delta Backup] Fix `Cannot read property 'uuid' of undefined` when a VDI has been removed from a backed up VM (PR [#6034](https://github.com/vatesfr/xen-orchestra/pull/6034))
 
 ### Released packages
@@ -340,7 +340,7 @@
 
 ### Bug fixes
 
-- [SDN Controller] Private network creation failure when the tunnels were created on different devices [Forum #4620](https://xcp-ng.org/forum/topic/4620/no-pif-found-in-center) (PR [#5793](https://github.com/vatesfr/xen-orchestra/pull/5793))
+- [SDN Controller] Private network creation failure when the tunnels were created on different devices [Forum#4620](https://xcp-ng.org/forum/topic/4620/no-pif-found-in-center) (PR [#5793](https://github.com/vatesfr/xen-orchestra/pull/5793))
 
 ### Released packages
 
diff --git a/CHANGELOG.unreleased.md b/CHANGELOG.unreleased.md
index 68ca3133770..8f22626ad5b 100644
--- a/CHANGELOG.unreleased.md
+++ b/CHANGELOG.unreleased.md
@@ -7,12 +7,11 @@
 
 > Users must be able to say: “Nice enhancement, I'm eager to test it”
 
-- Limit number of concurrent VM migrations per pool to `3` [#6065](https://github.com/vatesfr/xen-orchestra/issues/6065) (PR [#6076](https://github.com/vatesfr/xen-orchestra/pull/6076))
-  Can be changed in `xo-server`'s configuration file: `xapiOptions.vmMigrationConcurrency`
-- [Proxy] Now ships a reverse proxy [PR#6072](https://github.com/vatesfr/xen-orchestra/pull/6072)
-- [Delta Backup] When using S3 remote, retry uploading VHD parts on Internal Error to support [Blackblaze](https://www.backblaze.com/b2/docs/calling.html#error_handling) (PR [#6086](https://github.com/vatesfr/xen-orchestra/issues/6086)) (Forum [5397](https://xcp-ng.org/forum/topic/5397/delta-backups-failing-aws-s3-uploadpartcopy-cpu-too-busy/5))
-- [Backup] Add sanity check of aliases on S3 remotes (PR [6043](https://github.com/vatesfr/xen-orchestra/pull/6043))
-- [Export/Disks] Allow the export of disks in VMDK format(PR [#5982](https://github.com/vatesfr/xen-orchestra/pull/5982))
+- Limit number of concurrent VM migrations per pool to `3`. Can be changed in `xo-server`'s configuration file: `xapiOptions.vmMigrationConcurrency` [#6065](https://github.com/vatesfr/xen-orchestra/issues/6065) (PR [#6076](https://github.com/vatesfr/xen-orchestra/pull/6076))
+- [Proxy] Now ships a reverse proxy (PR [#6072](https://github.com/vatesfr/xen-orchestra/pull/6072))
+- [Delta Backup] When using S3 remote, retry uploading VHD parts on Internal Error to support [Blackblaze](https://www.backblaze.com/b2/docs/calling.html#error_handling) [Forum#5397](https://xcp-ng.org/forum/topic/5397/delta-backups-failing-aws-s3-uploadpartcopy-cpu-too-busy/5) (PR [#6086](https://github.com/vatesfr/xen-orchestra/issues/6086))
+- [Backup] Add sanity check of aliases on S3 remotes (PR [#6043](https://github.com/vatesfr/xen-orchestra/pull/6043))
+- [Export/Disks] Allow the export of disks in VMDK format (PR [#5982](https://github.com/vatesfr/xen-orchestra/pull/5982))
 - [Rolling Pool Update] Automatically pause load balancer plugin during the update [#5711](https://github.com/vatesfr/xen-orchestra/issues/5711)
 - [Backup] Speedup merge and cleanup speed for S3 backup by a factor 10 (PR [#6100](https://github.com/vatesfr/xen-orchestra/pull/6100))
 ### Bug fixes
@@ -21,6 +20,10 @@
 
 - [Backup] Detect and clear orphan merge states, fix `ENOENT` errors (PR [#6087](https://github.com/vatesfr/xen-orchestra/pull/6087))
 - [Backup] Ensure merges are also executed after backup on S3, maintaining the size of the VHD chain under control [Forum#45743](https://xcp-ng.org/forum/post/45743) (PR [#6095](https://github.com/vatesfr/xen-orchestra/pull/6095))
+- [Backup] Delete backups immediately instead of waiting for the next backup (PR [#6081](https://github.com/vatesfr/xen-orchestra/pull/6081))
+- [Backup] Delete S3 backups completely, even if there are more than 1000 files (PR [#6103](https://github.com/vatesfr/xen-orchestra/pull/6103))
+- [Backup] Fix merge resuming (PR [#6099](https://github.com/vatesfr/xen-orchestra/pull/6099))
+- [Plugin/Audit] Fix `key cannot be 'null' or 'undefined'` error when no audit log in the database [#6040](https://github.com/vatesfr/xen-orchestra/issues/6040) (PR [#6071](https://github.com/vatesfr/xen-orchestra/pull/6071))
 
 ### Packages to release
 
@@ -45,5 +48,6 @@
 - @xen-orchestra/backups minor
 - @xen-orchestra/backups-cli minor
 - @xen-orchestra/proxy minor
+- xo-server-audit patch
 - xo-server minor
 - xo-web minor
diff --git a/packages/vhd-lib/merge.js b/packages/vhd-lib/merge.js
index 5e7083c27c1..c12054d663b 100644
--- a/packages/vhd-lib/merge.js
+++ b/packages/vhd-lib/merge.js
@@ -38,22 +38,15 @@ module.exports = limitConcurrency(2)(async function merge(
   const mergeStatePath = dirname(parentPath) + '/' + '.' + basename(parentPath) + '.merge.json'
 
   return await Disposable.use(async function* () {
-    let mergeState = await parentHandler
-      .readFile(mergeStatePath)
-      .then(content => {
-        const state = JSON.parse(content)
-
-        // ensure the correct merge will be continued
-        assert.strictEqual(parentVhd.header.checksum, state.parent.header)
-        assert.strictEqual(childVhd.header.checksum, state.child.header)
-
-        return state
-      })
-      .catch(error => {
-        if (error.code !== 'ENOENT') {
-          warn('problem while checking the merge state', { error })
-        }
-      })
+    let mergeState
+    try {
+      const mergeStateContent = await parentHandler.readFile(mergeStatePath)
+      mergeState = JSON.parse(mergeStateContent)
+    } catch (error) {
+      if (error.code !== 'ENOENT') {
+        warn('problem while checking the merge state', { error })
+      }
+    }
 
     // during merging, the end footer of the parent can be overwritten by new blocks
     // we should use it as a way to check vhd health
@@ -70,6 +63,9 @@ module.exports = limitConcurrency(2)(async function merge(
       const parentDiskType = parentVhd.footer.diskType
       assert(parentDiskType === DISK_TYPES.DIFFERENCING || parentDiskType === DISK_TYPES.DYNAMIC)
       assert.strictEqual(childVhd.footer.diskType, DISK_TYPES.DIFFERENCING)
+    } else {
+      assert.strictEqual(parentVhd.header.checksum, mergeState.parent.header)
+      assert.strictEqual(childVhd.header.checksum, mergeState.child.header)
     }
 
     // Read allocation table of child/parent.
diff --git a/packages/xo-server-audit/src/index.js b/packages/xo-server-audit/src/index.js
index babb8afd18c..acd1edba0f6 100644
--- a/packages/xo-server-audit/src/index.js
+++ b/packages/xo-server-audit/src/index.js
@@ -396,12 +396,12 @@ class AuditXoPlugin {
   }
 
   async _generateFingerprint(props) {
-    const { oldest = NULL_ID, newest = await this._storage.getLastId() } = props
+    const { oldest = NULL_ID, newest = (await this._storage.getLastId()) ?? NULL_ID } = props
     try {
       return {
         fingerprint: `${oldest}|${newest}`,
         newest,
-        nValid: await this._checkIntegrity({ oldest, newest }),
+        nValid: newest !== NULL_ID ? await this._checkIntegrity({ oldest, newest }) : 0,
         oldest,
       }
     } catch (error) {