VMware Cannot Open Configuration File VMX: All Causes, All Fixes, and How to Recover When Data Is at Risk

When VMware Workstation or ESXi throws the error “Cannot open configuration file .vmx”, it usually signals a critical problem with the virtual machine’s metadata. The .vmx file is the core configuration file that defines a VM’s hardware settings, disk mappings, and runtime parameters — without it, VMware cannot boot the guest. This issue can arise from corrupted files, failed migrations, accidental deletions, or storage layer problems. For IT administrators and developers, the error can mean downtime, lost productivity, or even potential data loss if not addressed quickly. In this guide, we’ll break down the common causes of .vmx errors, practical fixes you can apply, and recovery strategies to restore your VM environment safely.

Cannot open the configuration file /vmfs/volumes/[datastore]/[VM directory]/[VMname].vmx

Cause 1: Stale .vmx~ Temporary File — ESXi Fix

Why the .vmx~ File Gets Left Behind

When ESXi powers on a VM, it creates a temporary working copy of the configuration file named .vmx~. This file is normally deleted when the VM powers off. If the host crashes, loses power, or encounters a storage fault mid‑operation, the cleanup never happens. On the next power‑on attempt, ESXi tries to create a new .vmx~ file but fails with errno: 17 (The file already exists), resulting in the “vmware cannot open configuration file vmx” error.

Step‑by‑Step Fix: Remove the Stale .vmx~ File (ESXi SSH)

This procedure follows VMware/Broadcom KB 308383:

1. 1. Open SSH session to the ESXi host where the VM is registered.
2. 2. Navigate to the VM’s directory on the datastore:

cd /vmfs/volumes/[datastore]/[VM directory] ls -ltrah

1. 3. Confirm the presence of a file ending in ~ (e.g., VMname.vmx~).
2. 4. Check for active locks on VM files:

for file in *; do vmfsfilelockinfo -p "$file" | awk '{FS = "\n"; RS = ""} {print $2 , $7}'; done

1. 5. Verify VM registration and ID:

vim-cmd vmsvc/getallvms

1. 6. Confirm VM is powered off:

vim-cmd vmsvc/power.getstate [vmid]

1. 7. Rename the stale file to avoid blocking startup:

mv VMname.vmx~ VMname.vmx_bak

1. 8. Power on the VM:

vim-cmd vmsvc/power.on [vmid]

1. 9. Delete the backup file once the VM is running successfully. Keep it until the VM powers on, as it may serve as a fallback.

ls | while read x; do vmfsfilelockinfo -p $x | grep -i "is locked"; done

lsof | egrep 'VMname.vmx'

esxcli vm process list

/etc/init.d/hostd restart /etc/init.d/vpxa restart

Cause 3: Permission Denied on NFS Datastore

Why NFS Permissions Block VMX Access

The errno: 13 (Permission denied) error occurs when the ESXi host lacks proper read/write access to the NFS export hosting the datastore. The most common culprit is root_squash, which maps ESXi’s root UID (0) to an anonymous user. This prevents ESXi from acquiring the exclusive lock it needs on the .vmx file. For VMware environments, the NFS export must be configured with no_root_squash to allow ESXi to function correctly.

Fix: NFS Export Permissions

1. 1. On the NFS server, verify export options for the datastore share. Ensure no_root_squash is set (not root_squash).
2. 2. Confirm the ESXi host’s IP address is explicitly listed in the NFS export’s allowed host list with rw (read/write) permissions.
3. 3. On the ESXi host, rescan the storage adapter after fixing NFS permissions:

• Navigate to Storage → Adapters → Rescan All.

1. 4. Attempt to power on the VM again. If the error persists, check whether the datastore is mounted read‑only (visible in datastore properties as Access: Read Only). If so, unmount and remount with read/write access.

When Fixes Fail: Recovering VMX and VMDK Data from a Damaged VMFS Datastore

What to Do When the Datastore Itself Is the Problem

All four causes above assume the VMFS datastore is accessible. If the datastore itself is offline — due to controller failure, LUN reassignment, VMFS metadata corruption, or ESXi host failure — the .vmx file cannot be opened because the filesystem containing it cannot be mounted. In these cases, standard ESXi troubleshooting commands return no output. The data still resides on the physical storage but is unreachable through normal VMware paths.

Why Standard Recovery Tools Cannot Read VMFS

VMFS is VMware’s proprietary clustered filesystem. Tools designed for NTFS, ext4, APFS, or FAT32 cannot parse VMFS structures, interpret VMDK descriptor files, or reconstruct snapshot delta chains. Recovering .vmx and .vmdk files from a damaged or offline VMFS datastore requires a tool that natively understands VMFS.

DiskInternals VMFS Recovery™: VMX and VMDK Recovery from Inaccessible Datastores

DiskInternals VMFS Recovery™ is purpose‑built for VMware environments. It can:

• Mount VMDK files directly without a running ESXi host — critical when the hypervisor is unavailable.
• Recover deleted .vmx configuration files from VMFS volumes.
• Reconstruct VMFS volumes with corrupted or partially overwritten metadata.
• Connect directly to ESXi servers via IP and credentials for remote datastore scanning.
• Provide file preview before extraction to confirm integrity.

Recommended workflow:

1. 1. Connect DiskInternals VMFS Recovery™ to the affected VMFS volume or ESXi host.
2. 2. Run a full scan to detect recoverable files.
3. 3. Locate .vmx and .vmdk files in the recovery browser.
4. 4. Preview file integrity before extraction.
5. 5. Extract recovered files to a safe destination.
6. 6. Re‑register the VM using the rebuilt .vmx file (see Fix Option 2 above).

Prevention: Stopping "Cannot Open Configuration File VMX" Before It Happens

Use vSphere HA and Proper Power‑Off Procedures

Most cannot open configuration file vmx errors stem from abrupt host failures — power cuts, kernel panics, or forced VM terminations — that leave lock files and temporary VMX copies behind. Configure vSphere HA on production clusters so VMs restart automatically after host failures. Always shut down VMs via the vSphere Client’s “Shut Down Guest OS” option instead of cutting power directly.

Maintain Regular VMX File Backups

VMX files are plain text, only a few kilobytes in size, yet they contain the complete hardware blueprint for a VM. Back them up daily. A simple script can compress and archive every VMX file across datastores in seconds. The cost is negligible, but the recovery value when a VMX file is deleted or corrupted is immediate.

Monitor NFS Datastores for Permission Drift

NFS export permissions can change after OS updates, firmware upgrades, or infrastructure modifications. Add NFS mount permission verification to quarterly audits. Always confirm no_root_squash is set on VMware NFS exports after storage maintenance to prevent permission‑denied errors.

Clean Up Snapshots to Prevent Lock Chain Complexity

Snapshot chains that grow beyond three levels increase the risk of lock conflicts during power‑on and backup operations. Consolidate snapshots regularly. ESXi 7.x and 8.x raise alerts for VMs with snapshot chains exceeding 100 GB — act on these alerts promptly to avoid lock failures.

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