content/posts/windows-backup/index.md

   1 ---
   2 title: "Windows Backup fails with 0x81000037? Check your filesystem"
   3 date: 2023-08-17T17:58:49+02:00
   4 summary: A weird issue with Windows Backup and how I fixed it.
   5 ---
   6 ## The Problem
   7 Yesterday, in preparation for a "downgrade" to Windows 10 from 11, I was trying
   8 to make a backup of my Windows files *(using the Windows 7 Backup and Restore
   9 control panel)*. Not long after it actually started copying the files, it spat
  10 out this error:
  11
  12 `Windows Backup failed while trying to read from the shadow copy on one of the
  13 volumes being backed up. Please check in the event logs for any relevant
  14 errors.`
  15
  16 The error code listed was `0x81000037`, and the first thing I did out of
  17 instinct was look this code up. The [official Microsoft support
  18 topic](https://support.microsoft.com/en-us/topic/windows-backup-or-restore-errors-0x80070001-0x81000037-or-0x80070003-e63576a2-22c9-8e90-bdde-e51a9e8e1893)
  19 stated that this error is caused if a reparse point *(Windows slang for
  20 symlink)* points to a FAT volume or is located on a volume containing compressed
  21 files. The listed workaround for this error is to delete the offending reparse
  22 point, and to locate it the topic suggests using the command `dir /al /s`, which
  23 is roughly equivalent to `find -type l` in Unix-like systems.
  24
  25 The first roadblock occurred when I found out that there is no offending reparse
  26 point which could cause this error, so I consulted `eventvwr` and found out that
  27 Windows Backup leaves some logs at `%WINDIR%\Logs\WindowsBackup`. It seemed to
  28 me that there are certain cache files that caused it to fail, so I deleted them
  29 and tried again. The backup again failed and I tried doing this a few more
  30 times, but as nothing helped I eventually gave up.
  31
  32 ## The Solution
  33 Having been unable to fix Windows' backup utility, I decided to just copy the
  34 files to the backup drive and copy them over back after the "downgrade". This is
  35 when the actual solution to my problem becomes visible: Windows Explorer
  36 errored, I forgot the exact message by now but it went something like *"The file
  37 XYZ is not available at the location"* or something, searching for the exact
  38 message is as pointless as always.
  39
  40 This usually indicates filesystem errors, so I ran `chkdsk C:` and,
  41 unsurprisingly, it found errors on the filesystem. Besides others, it mentions
  42 the files XYZ that couldn't be copied to the backup drive. I ran `chkdsk /scan
  43 C:`, rebooted through the filesystem error notification that popped up right
  44 after *(`chkdsk /f C:` and reboot will work as well)* and let it fix the errors.
  45 Once it rebooted, the backup completed without errors. After installing Windows
  46 10, restoring the backup was a breeze *(I only had AppData to back up,
  47 everything else was already on other drives)* and so I was quickly up and
  48 running, then amazed by how fast and snappy Windows 10 is compared to its
  49 "successor", but that's worthy of a separate post.
  50
  51 (I don't expect to get around to writing such post anytime soon though.)
  52
  53 ## *"Why are you writing about this?"*
  54 As you may know, Microsoft stuff is notorious for being not very well documented
  55 and it's entirely possible *(even if very unlikely)* that someone else encounters
  56 the same issue I have and is left helpless thanks to Windows' lack of a
  57 **proper, easy-to-use, centralized and well-written technical documentation
  58 system** *(think of `man`'s sections 4, 5, 7 and 8 for an idea of what I mean)*,
  59 not to mention countless YouTubers that parrot the same solutions as mentioned
  60 on the web many times before. I hope that this article will be useful to the one
  61 or so person with the same issue that may stumble upon it.
  62
  63 TLDR: Nobody seems to have mentioned this before *(please correct me if I'm
  64 wrong)*, so might as well help the potential other person stuck in the same boat
  65 as me.