Stop all disk writes immediately if you suspect the backup disk is failing, otherwise confirm the disk is powered, mounted in Finder, and click Back Up Now from the Time Machine menu. If a time machine backup stuck on “Preparing” still won’t move, work through the checklist below, starting with the least invasive fix. Some stalls may clear with basic troubleshooting, but avoid changes that could put data at risk.
TL;DR:
- Connect the disk directly, bypass hubs, pause sync and antivirus tools, then restart and choose Back Up Now to test for network trouble.
- Run First Aid on each volume, then the container, then the physical device; if it repeatedly fails or warns of disk failure, stop all writes.
- Apple says interrupted backups usually resume automatically, so remove the .inProgress marker only when a stall persists; if it returns, suspect corruption or a busy volume.
- Use APFS or APFS Encrypted when possible; Apple recommends a backup disk with at least twice your Mac’s storage, and reformatting erases every backup.
- Large, frequently changing files, sync activity, and Spotlight indexing can prolong preparation; temporarily exclude virtual machine images, mail caches, or large Photos libraries.
Run these in order. These checks are intended to be non-destructive, but take care to avoid changes that could put data at risk.
Pro Tip: Don’t see the Time Machine icon? Turn it on in System Settings > Control Center > Time Machine, so you can watch progress and start manual backups.
Apple’s own troubleshooting guidance says to connect the backup disk directly instead of through a hub and to check free space on both the Mac and the backup disk.
Open Disk Utility, choose View > Show All Devices, and run First Aid in this order: each volume, then the container, then the physical device at the top of the tree. Running them bottom-up and then top-down catches directory problems at every layer, which is where many stalled backups begin.
Disk Utility’s First Aid can repair directory-level issues but can’t fix every problem. If it says the disk is about to fail, back up what you can and stop repair attempts. Each extra write is a risk to your data.
An interrupted backup may leave a marker file. Apple says an interrupted backup usually resumes on its own, so avoid removing files from the backup unless you know what they are. Apple confirms that an interrupted backup usually resumes on its own, so only do this when the stall persists.
If the .inProgress file keeps reappearing and the backup stalls at the same point, suspect disk corruption or a volume that something else keeps busy. Move to the format and escalation sections rather than repeating this step.
A wrong format or a nearly full disk quietly stalls backups. Select the drive in Finder and choose Get Info, or check it in Disk Utility, to see its format and capacity.
An unstable network is a leading cause of stalled remote backups, and the fastest test is to remove the network from the equation.
Make sure the Mac and the backup device sit on the same network, as Apple’s troubleshooting page notes.
Apps that lock or constantly rewrite files make backups crawl. Apple notes that large or frequently changing files and third-party utilities can keep the backup disk busy.
Pro Tip: Exclude the heavy folders temporarily, finish one clean backup, then remove the exclusions you don’t need. You get a healthy baseline without losing long-term coverage.
Knowing the cause saves you from repeating fixes that can’t work.
Stop all disk writes immediately if Disk Utility says the disk is about to fail, First Aid keeps failing, or the drive disconnects at random or makes unusual noises. More repair attempts on failing hardware can turn recoverable data into lost data.
In our lab, the order is always the same: preserve the data, then run non-destructive checks like First Aid and a direct connection. A failing backup drive may show warning signs. Stopping writes when a problem appears can help protect data. Since 2006, we’ve focused on protecting data before attempting repairs.
— Kaya
When a backup disk or your Mac itself is failing, a same-day appointment beats another night of guessing. Our lab handles data recovery for Macs, hard drives, SSDs, and RAID systems, and we repair logic boards at the component level.
Large or frequently changing files, an interrupted earlier backup, or software that keeps the disk busy are the usual causes. Excluding heavy folders and pausing sync apps often brings the time back to normal.
Check that the disk is connected directly, formatted as APFS, and has enough free space. A failing disk can also refuse backups, so run First Aid and stop if it reports serious errors.
Open Time Machine settings, select the disk, and click the minus button to remove it. Removing it from the list doesn’t erase the backups on the disk.
It depends on how much data changed and how fast the connection is. A first backup or one after an interruption can take longer. If preparation appears stalled, check the causes listed above.
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