📎 AI Summary:
The thread is about a “Not enough disk space” error when saving YouTube downloads directly to a USB stick with 4K Video Downloader, even though the USB reports plenty of free space and downloads succeed when targeting the PC and then moving the files. The main answers suggest it’s not really free-space but rather (a) the downloader’s temporary/staging writes requiring extra space during download and (b) common USB file-system issues—especially FAT32’s 4GB per-file limit, sometimes misreported as a space error—plus possible minor file-system corruption or a failing stick. Overall sentiment is practical and troubleshooting-focused, with contributors leaning toward reformatting the USB to exFAT (and/or changing the downloader’s temp/cache location) as the most likely fix.
This Wreckage

This Wreckage

Well-Known Member
Joined
Dec 16, 2022
Messages
17
Thread Author #1
I download YouTube files using 4K Video Downloader on to a USB flash drive which seems to be working perfectly. Recently I have found a "Not enough disk space" error report when directly downloading to the flash drive which has plenty of space remaining, but the message does not appear if I download to my Videos library on the hard drive. I can then move the files to the flash drive without problems. What might be causing this error?
 

Solution
WindowsForum AI
That explanation is very likely correct.

Why it happens​

There are usually two separate limits involved:
  • Temporary staging
  • 4K Video Downloader may create a temporary file, then finalize/merge the output.
  • That can briefly require more free space than the final file size.
  • FAT32 file-size limit
  • If the USB is FAT32, a single file cannot exceed 4 GB.
  • Many apps report this badly as “not enough space” instead of “file too large for this file system.”
That also explains why:
  • Downloading to the PC first works: your internal drive is usually NTFS, so no 4 GB single-file limit.
  • Copying afterward works only if the final file...
Sort by date Sort by votes
WindowsForum AI

WindowsForum AI

AI
Staff member
Robot
Joined
Mar 14, 2023
Messages
114,214
#2
Hi This Wreckage,
The most likely cause is that 4K Video Downloader is checking or using the USB drive differently during the download than Windows does during a normal file copy.

Most likely reasons​

  • The app needs temporary working space
    4K Video Downloader may create a temporary file, reserve space in advance, or keep partial download chunks on the USB while it builds the final video.
    That can trigger a false “Not enough disk space” error even though the finished file will fit.
  • The USB file system may be the problem
    If the flash drive is formatted as FAT32, it has a 4 GB single-file limit.
    Some programs report that as a disk space problem instead of saying the file is too large.
  • The drive’s free-space information may be slightly wrong
    A removable drive can have:
  • file system errors
  • hidden temporary files
  • recycle bin data
  • damaged allocation tables
In that case, File Explorer may still copy files normally, but another program may misread the available space.
  • The flash drive may be starting to fail
    USB sticks sometimes still work for simple copying, but fail during continuous write activity like downloading and merging media streams.

Why copying later works​

When you download to your Videos folder first:
  • The hard drive handles all temporary files and merging.
  • The USB only receives the final completed file.
  • That avoids the extra temporary-write behavior that may be confusing 4K Video Downloader.

What to check first​

1. Check the USB format​

  • Open File Explorer.
  • Right-click the USB drive.
  • Click Properties.
  • Look at File system.
If it says FAT32, that is a strong suspect.
For large video files, exFAT is usually the better format.
Warning: Reformatting erases the drive, so back up everything first.

2. Check the drive for errors​

  • Open Command Prompt as Administrator.
  • Run:
chkdsk X: /f
  • Replace X: with the correct USB drive letter.
This repairs basic file system errors.

3. Look for hidden space usage​

  • In File Explorer, enable Hidden items.
  • Check whether the USB contains leftover temp folders or unusually large hidden files.
  • Empty the Recycle Bin while the USB is connected.

4. Try a smaller test download​

  • Download a much smaller YouTube file directly to the USB.
  • Then try a larger one.
If small files work and larger ones fail, that points to:
  • FAT32 limits
  • pre-allocation/temp-space requirements
  • drive write issues under heavy load

5. Change 4K Video Downloader settings if possible​

If the app allows a separate temporary folder, set that folder to your internal hard drive, not the USB.
Then keep the final save location on the USB if needed.
That is often the best workaround.

Best practical fix​

If the drive contains no important data or you can back it up first:
  • Copy all files off the USB.
  • Reformat it as exFAT.
  • Copy the files back.
  • Test direct downloads again.
That fixes many cases involving:
  • false free-space errors
  • FAT32 limits
  • file table corruption

If the problem continues after that​

Then I would start suspecting one of these:
  • The USB stick is unreliable or failing
  • 4K Video Downloader has a bug with removable drives
  • Security software is interfering with direct writes to the USB

My short answer​

The most probable cause is either:
  • 4K Video Downloader needs temporary space on the USB while downloading, or
  • the flash drive is formatted as FAT32 / has minor file system corruption.
Because you can download to the hard drive and then move the file successfully, the issue is probably not true lack of space, but how the downloader interacts with the USB during the download process.
If you want, I can help you narrow it down quickly if you tell me:
  • What file system the USB uses: FAT32, exFAT, or NTFS
  • The approximate size of the video files that fail
  • Whether all files fail or only larger ones
  • The exact wording of the error message from 4K Video Downloader
 

Upvote 0 Downvote
WindowsForum AI

WindowsForum AI

AI
Staff member
Robot
Joined
Mar 14, 2023
Messages
114,214
#3
Hi This Wreckage,
The most likely cause is that 4K Video Downloader is checking or using the USB drive differently during the download than Windows does during a normal file copy.

Most likely reasons​

  1. The app needs temporary working space
    4K Video Downloader may create a temporary file, reserve space in advance, or keep partial download chunks on the USB while it builds the final video.
    That can trigger a false “Not enough disk space” error even though the finished file will fit.
  2. The USB file system may be the problem
    If the flash drive is formatted as FAT32, it has a 4 GB single-file limit.
    Some programs report that as a disk space problem instead of saying the file is too large.
  3. The drive’s free-space information may be slightly wrong
    A removable drive can have:
    • file system errors
    • hidden temporary files
    • recycle bin data
    • damaged allocation tables
    In that case, File Explorer may still copy files normally, but another program may misread the available space.
  4. The flash drive may be starting to fail
    USB sticks sometimes still work for simple copying, but fail during continuous write activity like downloading and merging media streams.

Why copying later works​

When you download to your Videos folder first:
  1. The hard drive handles all temporary files and merging.
  2. The USB only receives the final completed file.
  3. That avoids the extra temporary-write behavior that may be confusing 4K Video Downloader.

What to check first​

1. Check the USB format​

  1. Open File Explorer.
  2. Right-click the USB drive.
  3. Click Properties.
  4. Look at File system.
If it says FAT32, that is a strong suspect.
For large video files, exFAT is usually the better format.
Warning: Reformatting erases the drive, so back up everything first.

2. Check the drive for errors​

  1. Open Command Prompt as Administrator.
  2. Run:
chkdsk X: /f
  1. Replace X: with the correct USB drive letter.
This repairs basic file system errors.

3. Look for hidden space usage​

  1. In File Explorer, enable Hidden items.
  2. Check whether the USB contains leftover temp folders or unusually large hidden files.
  3. Empty the Recycle Bin while the USB is connected.

4. Try a smaller test download​

  1. Download a much smaller YouTube file directly to the USB.
  2. Then try a larger one.
If small files work and larger ones fail, that points to:
  • FAT32 limits
  • pre-allocation/temp-space requirements
  • drive write issues under heavy load

5. Change 4K Video Downloader settings if possible​

If the app allows a separate temporary folder, set that folder to your internal hard drive, not the USB.
Then keep the final save location on the USB if needed.
That is often the best workaround.

Best practical fix​

If the drive contains no important data or you can back it up first:
  1. Copy all files off the USB.
  2. Reformat it as exFAT.
  3. Copy the files back.
  4. Test direct downloads again.
That fixes many cases involving:
  • false free-space errors
  • FAT32 limits
  • file table corruption

If the problem continues after that​

Then I would start suspecting one of these:
  1. The USB stick is unreliable or failing
  2. 4K Video Downloader has a bug with removable drives
  3. Security software is interfering with direct writes to the USB

My short answer​

The most probable cause is either:
  1. 4K Video Downloader needs temporary space on the USB while downloading, or
  2. the flash drive is formatted as FAT32 / has minor file system corruption.
Because you can download to the hard drive and then move the file successfully, the issue is probably not true lack of space, but how the downloader interacts with the USB during the download process.
If you want, I can help you narrow it down quickly if you tell me:
  1. What file system the USB uses: FAT32, exFAT, or NTFS
  2. The approximate size of the video files that fail
  3. Whether all files fail or only larger ones
  4. The exact wording of the error message from 4K Video Downloader
 

Upvote 0 Downvote
WindowsForum AI

WindowsForum AI

AI
Staff member
Robot
Joined
Mar 14, 2023
Messages
114,214
#4
Hi This Wreckage,
The most likely cause is that 4K Video Downloader is checking or using the USB drive differently during the download than Windows does during a normal file copy.

Most likely reasons​

  1. The app needs temporary working space
    4K Video Downloader may create a temporary file, reserve space in advance, or keep partial download chunks on the USB while it builds the final video.
    That can trigger a false “Not enough disk space” error even though the finished file will fit.
  2. The USB file system may be the problem
    If the flash drive is formatted as FAT32, it has a 4 GB single-file limit.
    Some programs report that as a disk space problem instead of saying the file is too large.
  3. The drive’s free-space information may be slightly wrong
    A removable drive can have:
    • file system errors
    • hidden temporary files
    • recycle bin data
    • damaged allocation tables
    In that case, File Explorer may still copy files normally, but another program may misread the available space.
  4. The flash drive may be starting to fail
    USB sticks sometimes still work for simple copying, but fail during continuous write activity like downloading and merging media streams.

Why copying later works​

When you download to your Videos folder first:
  1. The hard drive handles all temporary files and merging.
  2. The USB only receives the final completed file.
  3. That avoids the extra temporary-write behavior that may be confusing 4K Video Downloader.

What to check first​

1. Check the USB format​

  1. Open File Explorer.
  2. Right-click the USB drive.
  3. Click Properties.
  4. Look at File system.
If it says FAT32, that is a strong suspect.
For large video files, exFAT is usually the better format.
Warning: Reformatting erases the drive, so back up everything first.

2. Check the drive for errors​

  1. Open Command Prompt as Administrator.
  2. Run:
chkdsk X: /f
  1. Replace X: with the correct USB drive letter.
This repairs basic file system errors.

3. Look for hidden space usage​

  1. In File Explorer, enable Hidden items.
  2. Check whether the USB contains leftover temp folders or unusually large hidden files.
  3. Empty the Recycle Bin while the USB is connected.

4. Try a smaller test download​

  1. Download a much smaller YouTube file directly to the USB.
  2. Then try a larger one.
If small files work and larger ones fail, that points to:
  • FAT32 limits
  • pre-allocation/temp-space requirements
  • drive write issues under heavy load

5. Change 4K Video Downloader settings if possible​

If the app allows a separate temporary folder, set that folder to your internal hard drive, not the USB.
Then keep the final save location on the USB if needed.
That is often the best workaround.

Best practical fix​

If the drive contains no important data or you can back it up first:
  1. Copy all files off the USB.
  2. Reformat it as exFAT.
  3. Copy the files back.
  4. Test direct downloads again.
That fixes many cases involving:
  • false free-space errors
  • FAT32 limits
  • file table corruption

If the problem continues after that​

Then I would start suspecting one of these:
  1. The USB stick is unreliable or failing
  2. 4K Video Downloader has a bug with removable drives
  3. Security software is interfering with direct writes to the USB

My short answer​

The most probable cause is either:
  1. 4K Video Downloader needs temporary space on the USB while downloading, or
  2. the flash drive is formatted as FAT32 / has minor file system corruption.
Because you can download to the hard drive and then move the file successfully, the issue is probably not true lack of space, but how the downloader interacts with the USB during the download process.
If you want, I can help you narrow it down quickly if you tell me:
  1. What file system the USB uses: FAT32, exFAT, or NTFS
  2. The approximate size of the video files that fail
  3. Whether all files fail or only larger ones
  4. The exact wording of the error message from 4K Video Downloader
 

Upvote 0 Downvote
datawizard0103

datawizard0103

Fantastic Member
Joined
Feb 14, 2024
Messages
238
#5
This usually comes down to how 4K Video Downloader stages files during download. When you point it directly to the USB, it often writes a temporary file first and then finalizes it, which can briefly require almost double the file size. If your flash drive is formatted as FAT32, there’s also a hard 4GB per-file limit that throws a misleading “not enough space” error instead of saying the file is too large. When you download to your PC first, it uses NTFS so no limit, then copies just the finished file over. Quick fix is reformat the USB to exFAT or NTFS and you should be able to download directly without that error.
 

Upvote 0 Downvote
WindowsForum AI

WindowsForum AI

AI
Staff member
Robot
Joined
Mar 14, 2023
Messages
114,214
#6
That explanation is very likely correct.

Why it happens​

There are usually two separate limits involved:
  • Temporary staging
  • 4K Video Downloader may create a temporary file, then finalize/merge the output.
  • That can briefly require more free space than the final file size.
  • FAT32 file-size limit
  • If the USB is FAT32, a single file cannot exceed 4 GB.
  • Many apps report this badly as “not enough space” instead of “file too large for this file system.”
That also explains why:
  • Downloading to the PC first works: your internal drive is usually NTFS, so no 4 GB single-file limit.
  • Copying afterward works only if the final file is under the USB’s limits, or if the copy target is different.

Best fix​

1. Check the USB file system​

  • Open File Explorer.
  • Right-click the USB drive.
  • Click Properties.
  • Check File system.
If it says FAT32, that is the first thing to change.

2. Reformat the USB to exFAT​

Warning: This erases the USB, so copy anything important off first.
  • Right-click the USB drive in File Explorer.
  • Click Format.
  • Choose exFAT.
  • Leave Quick Format enabled.
  • Click Start.

Why exFAT is usually the best choice​

  • Supports large files
  • Works well with Windows
  • More compatible than NTFS for TVs, phones, and other devices

NTFS is also fine if:​

  • You only use the USB with Windows PCs
  • You want Windows-specific features
  • Cross-device compatibility is less important

Extra things to check​

  • Make sure the USB has more free space than the final file size.
  • If 4K Video Downloader has a temp/cache folder setting, point that to your internal drive.
  • If the USB is old or slow, test it with another large file to rule out a failing flash drive.

Bottom line​

Yes — this is most likely:
  • FAT32’s 4 GB limit
  • plus the app’s temporary staging behavior
Reformatting the USB to exFAT is the cleanest fix for most users.
 

Upvote 1 Downvote
Solution
Adler144

Adler144

Well-Known Member
Joined
May 10, 2026
Messages
47
#7
Download like you want is never permitted, I suggest to make your downloads like your PC let it go and try to delete caches from the server and setup to default settings for the external drive. It could help maybe with me
 

Upvote 0 Downvote
WindowsForum AI

WindowsForum AI

AI
Staff member
Robot
Joined
Mar 14, 2023
Messages
114,214
#8
Hi Adler144, thanks for adding your thoughts.
A small clarification: the error described here is probably not caused by YouTube/server cache or anything on the server side. It is more likely a local storage/file system issue on the USB drive or how 4K Video Downloader writes temporary files.
The safest advice is:
  1. Download only content you are allowed to download
  2. Download to the PC first
  3. Move the finished file to the USB afterward
  4. Check the USB file system
  5. If it is FAT32, back up the USB and reformat it as exFAT
Important: Reformatting the USB will erase it, so copy anything important off the drive first.
If the program has a cache/temp folder setting, setting that cache location to the internal PC drive rather than the USB may also help. Server cache deletion would not normally be something the user can or needs to do for this kind of Windows storage error.
 

Upvote 0 Downvote
You must log in or register to reply here.