Hi,I have an interesting issue where my typical transfer of images and data from my Samsung S20 FE device to my Win 11 Pro PC via the USB C cable is VERY slow - we're talking about 10 kb/s and less. Specifically, the issue seems to happen when my saved job tries to transfer the thumbnail folder (In the picture folder on the phone's internal storage).
In the past this transfer worked fine - I use FreeFileSync to backup my phones on a somewhat regular basis.
I'm using V14.3 - anyone else run into this issue?
The interesting part (to me) is that the transfer doesn't "fail", it continues on just VERY slowly. To transfer 12.1 GB it's estimating 20 days to complete. From what I can tell, the files that are transferred are transferred correctly.
The schema is this: my phone's files UPDATE the files on the PC. Nothing special, really.
The folders I backup:
Internal Storage (Phone) --> Videos, Pictures, Movies, Downloads, DCIM
SD Card Storage (Phone) --> DCIM
Bug? MTP transfer of Thumbnails from Android is very slow
- Posts: 8
- Joined: 17 Jun 2025
- Posts: 1202
- Joined: 8 May 2006
If you use some other method (other then FFS) to attempt similar, does the same slowness ensue?
(I suppose working on a subset of said data should give you an indication - cause, I'm probably going to be on vacation in 20 days ;-).)
(I suppose working on a subset of said data should give you an indication - cause, I'm probably going to be on vacation in 20 days ;-).)
- Posts: 8
- Joined: 17 Jun 2025
Thanks for the reply, therube!
So I just transferred the same thumbnail folder via the typical windows copy paste function and it completed the copy in about 25 minutes (I overwrote any existing files that FFS already transferred).
If it helps, the thumbnail folder is actually ".thumbnail" with some other "." hidden files in the folder (that I'd also like to copy over" but it's mostly just jpeg thumbnails around 10-100kb in size. This transfer with FFS used to work flawlessly, but something must have changed either in FFS or in the way Android presents files via mtp.
The thumbnail folder is around 750 MB with around 14000 files.
Threads are set to "1".
Curious - I tried the job again and since the thumbnails are done, it is quite a bit faster now. Still slow between 1-15 MB/sec but there's a lot of little files so I think it's acceptable.
So I just transferred the same thumbnail folder via the typical windows copy paste function and it completed the copy in about 25 minutes (I overwrote any existing files that FFS already transferred).
If it helps, the thumbnail folder is actually ".thumbnail" with some other "." hidden files in the folder (that I'd also like to copy over" but it's mostly just jpeg thumbnails around 10-100kb in size. This transfer with FFS used to work flawlessly, but something must have changed either in FFS or in the way Android presents files via mtp.
The thumbnail folder is around 750 MB with around 14000 files.
Threads are set to "1".
Curious - I tried the job again and since the thumbnails are done, it is quite a bit faster now. Still slow between 1-15 MB/sec but there's a lot of little files so I think it's acceptable.
-
- Posts: 4866
- Joined: 11 Jun 2019
I would exclude the thumbnail folders in the filters, not any good reason to back them up
- Posts: 162
- Joined: 5 Jan 2024
Hi,
I don't even have a folder called .thumbnails in that location and I have an s23. I used two file managers to display hidden files and found hidden files and folders but not that one.
I agree that these files don't need to be backed up they will be automatically created all over again if you just delete them. You probably have a whole bunch of thumbnails that are complete waste of space.
Anyway I did some comparisons regarding speed. I didn't use a cable I went Wireless and used both SFTP and SMB.
When transferring a large file they were both about the same 30 MB/sec. For smaller files the speed was closer to 20 and the winner between the two was SMB using a free SMB file server from the Google Play app store and the owl files file manager on Windows because you can't use port 445 on your cell phone so the SMB server uses Port 4445 and you need to program that can do Microsoft on Alternate port numbers and Owl files which is available in the Microsoft store gets the trick done the fastest of any method I've tested so far.
Sftp of course is what is most compatible with free file sync. I use a free SFTP server from the Play Store as well.
Might want to give those options a try and worst case scenario delete the entire thumbnail folder or make a backup copy of it before you delete it if it makes you feel more comfortable and your phone should and will automatically recreate those thumbnails as they are needed and the thumbnails that were created a year ago or more probably won't get recreated because you won't be accessing those files. The thumbnail folder should remain substantially smaller.
Also, I'm using the donation Edition of free file sync and I bumped the number of threads from one to eight and performance went from 17 MB per second to 30 MB.
Never liked cables.
I don't even have a folder called .thumbnails in that location and I have an s23. I used two file managers to display hidden files and found hidden files and folders but not that one.
I agree that these files don't need to be backed up they will be automatically created all over again if you just delete them. You probably have a whole bunch of thumbnails that are complete waste of space.
Anyway I did some comparisons regarding speed. I didn't use a cable I went Wireless and used both SFTP and SMB.
When transferring a large file they were both about the same 30 MB/sec. For smaller files the speed was closer to 20 and the winner between the two was SMB using a free SMB file server from the Google Play app store and the owl files file manager on Windows because you can't use port 445 on your cell phone so the SMB server uses Port 4445 and you need to program that can do Microsoft on Alternate port numbers and Owl files which is available in the Microsoft store gets the trick done the fastest of any method I've tested so far.
Sftp of course is what is most compatible with free file sync. I use a free SFTP server from the Play Store as well.
Might want to give those options a try and worst case scenario delete the entire thumbnail folder or make a backup copy of it before you delete it if it makes you feel more comfortable and your phone should and will automatically recreate those thumbnails as they are needed and the thumbnails that were created a year ago or more probably won't get recreated because you won't be accessing those files. The thumbnail folder should remain substantially smaller.
Also, I'm using the donation Edition of free file sync and I bumped the number of threads from one to eight and performance went from 17 MB per second to 30 MB.
Never liked cables.
- Posts: 8
- Joined: 17 Jun 2025
Hi all, thank you very much for taking the time to reply with your workarounds and suggestions.
Unfourtunately, that is what this is - workarounds. I posted this here to report a potential bug (or odd behaviour) in the software as my workflow has been working fine for about 5 years now.
In one of my replies I stated that a simple copy-paste in windows explorers works fine. What I am hoping for is an answer as to why this behaviour exists in the software now. Perhaps I'll never get an answer like that and that is okay. This forum will still hopefully serve as a place to post workarounds for those that are encountering issues with mtp transfers.
It might be a new thing with android as well, I don't know. Android has been getting worse and worse for out of ecosystem file transfers. I miss the days of using an android phone as a usb drive.
Unfourtunately, that is what this is - workarounds. I posted this here to report a potential bug (or odd behaviour) in the software as my workflow has been working fine for about 5 years now.
In one of my replies I stated that a simple copy-paste in windows explorers works fine. What I am hoping for is an answer as to why this behaviour exists in the software now. Perhaps I'll never get an answer like that and that is okay. This forum will still hopefully serve as a place to post workarounds for those that are encountering issues with mtp transfers.
It might be a new thing with android as well, I don't know. Android has been getting worse and worse for out of ecosystem file transfers. I miss the days of using an android phone as a usb drive.
- Posts: 162
- Joined: 5 Jan 2024
I understand and hear your frustration. There's nothing I can do to test or try and reproduce what you're having as a problem because I don't have a thumbnail folder like you do on my phone. I'm running Android 14 or now 15 I think and on a Samsung s23.
UPDATE:
Just found my hidden thumbnail folder under pictures. Mine is only 9 MB so it's probably going to work fine.
So thumbnails are:
Purpose: Stores cached thumbnail images for faster loading in gallery apps.
These are thumbnails of photos and videos already on the device.
Size Issues: Over time, this folder can grow quite large. Deleting its contents can free space, but thumbnails will be regenerated again later.
Perhaps you should try deleting the folder since you do have it backed up on your computer and let it restart itself over again and it will begin small and everything will probably work.
You have nothing to lose at this point by giving it a shot. It doesn't delete any of your photos or videos.
UPDATE:
Just found my hidden thumbnail folder under pictures. Mine is only 9 MB so it's probably going to work fine.
So thumbnails are:
Purpose: Stores cached thumbnail images for faster loading in gallery apps.
These are thumbnails of photos and videos already on the device.
Size Issues: Over time, this folder can grow quite large. Deleting its contents can free space, but thumbnails will be regenerated again later.
Perhaps you should try deleting the folder since you do have it backed up on your computer and let it restart itself over again and it will begin small and everything will probably work.
You have nothing to lose at this point by giving it a shot. It doesn't delete any of your photos or videos.
- Posts: 1202
- Joined: 8 May 2006
> I just transferred the same thumbnail folder via the typical windows copy paste function and it completed the copy in about 25 minutes
> mostly just <files> around 10-100kb in size
> The ... folder is around 750 MB with around 14000 files
Maybe it is just that.
Small size (so maybe "disk" cluster size is playing in ?) & the shear number 14K of files (in a single directory).
But then, there is still, "windows copy paste ... and it completed ... in about 25 minutes" (rather then 20 days).
So it is nothing to do with a ".thumbnails" directory, per se.
So excluding that accomplishes nothing.
(I know nothing of phones/android, "disk" on such, nor its' OS, format, efficiency that may or may not contribute... but then, the 'ol copy & paste did not have the issue...)
So that tends to point to... FFS, no?
So... if someone has a phone, & cares to copy a huge number of tiny files into a singular directory, & then have FFS copy same...
> mostly just <files> around 10-100kb in size
> The ... folder is around 750 MB with around 14000 files
Maybe it is just that.
Small size (so maybe "disk" cluster size is playing in ?) & the shear number 14K of files (in a single directory).
But then, there is still, "windows copy paste ... and it completed ... in about 25 minutes" (rather then 20 days).
So it is nothing to do with a ".thumbnails" directory, per se.
So excluding that accomplishes nothing.
(I know nothing of phones/android, "disk" on such, nor its' OS, format, efficiency that may or may not contribute... but then, the 'ol copy & paste did not have the issue...)
So that tends to point to... FFS, no?
So... if someone has a phone, & cares to copy a huge number of tiny files into a singular directory, & then have FFS copy same...
- Posts: 1202
- Joined: 8 May 2006
> we're talking about 10 kb/s and less
To be clear, we're at the Sync stage now, the scan itself has long finished & we're just copying (syncing) files.
db was mentioned (elsewhere).
Might that be playing in?
If db is recording 14K changes... & if the file sizes are so small that the actual copy is not the issue, but the recording of said transactions, where it "can't catch its' breath"...
If db does not apply to particular file system/protocol, is it still "used" (in some manner) such that it still might impede things (rather then simply NOOP & skipping entirely)?
To be clear, we're at the Sync stage now, the scan itself has long finished & we're just copying (syncing) files.
db was mentioned (elsewhere).
Might that be playing in?
If db is recording 14K changes... & if the file sizes are so small that the actual copy is not the issue, but the recording of said transactions, where it "can't catch its' breath"...
If db does not apply to particular file system/protocol, is it still "used" (in some manner) such that it still might impede things (rather then simply NOOP & skipping entirely)?
- Posts: 8
- Joined: 17 Jun 2025
That is correct, the scan stage actually completes rather quickly for the entire job, maybe around 60 seconds or so. The issue occurs during the sync stage.
I should double check my sync settings to see if that database is enabled... I have a feeling that it is enabled since I believe it is enabled by default for the UPDATE scheme. Can't recall though.
@John1234 - thank you for looking into this yourself! And yes, I agree that reducing the size of my thumbnail folder should pretty much fix the slow transfer with this particular sync job.
I have a work phone, a Pixel device, that I should apply the same job to and see if there is any difference. It's a relatively new device so it should have a significantly smaller thumbnail folder. (That being said, that changes the variables entirely here - perhaps useful in case it's actually the S20FE that's the issue here)
I should double check my sync settings to see if that database is enabled... I have a feeling that it is enabled since I believe it is enabled by default for the UPDATE scheme. Can't recall though.
@John1234 - thank you for looking into this yourself! And yes, I agree that reducing the size of my thumbnail folder should pretty much fix the slow transfer with this particular sync job.
I have a work phone, a Pixel device, that I should apply the same job to and see if there is any difference. It's a relatively new device so it should have a significantly smaller thumbnail folder. (That being said, that changes the variables entirely here - perhaps useful in case it's actually the S20FE that's the issue here)
- Posts: 162
- Joined: 5 Jan 2024
Here are my final thoughts on your predicament.
You're spending an awful lot of time and energy trying to back up a folder that is there merely for convenience purposes and it's not actually your real data.
If it were me I would skip or exclude the thumbnail folder from backups and in the event you have a loss of phone you still have all of your pictures and the thumbnail gets recreated on your new device.
I could not afford to spend as much time and energy as you are on this for yourself for one of my customers. I would simply say the folder needs to be excluded and that is the end of the discussion. There's no practical usefulness for the folder being backed up and it seems to be just a waste of time. I know that in theory it should work the way that you want it to but in reality it does not.
I would simply exclude the folder and move on.
I would go broke if I spent so much time working on such a trivial insignificant problem.
You're spending an awful lot of time and energy trying to back up a folder that is there merely for convenience purposes and it's not actually your real data.
If it were me I would skip or exclude the thumbnail folder from backups and in the event you have a loss of phone you still have all of your pictures and the thumbnail gets recreated on your new device.
I could not afford to spend as much time and energy as you are on this for yourself for one of my customers. I would simply say the folder needs to be excluded and that is the end of the discussion. There's no practical usefulness for the folder being backed up and it seems to be just a waste of time. I know that in theory it should work the way that you want it to but in reality it does not.
I would simply exclude the folder and move on.
I would go broke if I spent so much time working on such a trivial insignificant problem.
- Posts: 1202
- Joined: 8 May 2006
While the backing up (or lack thereof) of a "thumbnail" directory may be a "trivial insignificant" problem, if the issue is more generalized, then it is no longer a trivial insignificant problem.
If there is a problem here, if it is more generalized, such that the backup of your data, of your significant data, becomes impaired then is no longer, trivial.
Maybe there isn't an issue here.
Maybe it's just a quirk between the phone, the software, & the particular settings being used.
But then, maybe not.
And, Windows copy/paste does not exhibit the same behaviors.
If there is a problem here, if it is more generalized, such that the backup of your data, of your significant data, becomes impaired then is no longer, trivial.
Maybe there isn't an issue here.
Maybe it's just a quirk between the phone, the software, & the particular settings being used.
But then, maybe not.
And, Windows copy/paste does not exhibit the same behaviors.
- Posts: 162
- Joined: 5 Jan 2024
Agreed.
I would as a test in the next step of this process exclude the folder on purpose and do a comparison find out what it wants to do and run a test backup minus that one folder and see if all of the other data backs up normally and the customer is satisfied with the results. If everything works fine in the absence of that one hidden folder then case closed. If there's still a problem backing up all of his other files even though that folder is excluded then that's something else to investigate such as comparing how it works over Wi-Fi versus cable just to see how it differs.
I would as a test in the next step of this process exclude the folder on purpose and do a comparison find out what it wants to do and run a test backup minus that one folder and see if all of the other data backs up normally and the customer is satisfied with the results. If everything works fine in the absence of that one hidden folder then case closed. If there's still a problem backing up all of his other files even though that folder is excluded then that's something else to investigate such as comparing how it works over Wi-Fi versus cable just to see how it differs.
- Posts: 1202
- Joined: 8 May 2006
Fail-safe file copy & VerifyCopiedFiles mentioned:
viewtopic.php?t=10375
(Former default, latter not. Wouldn't expect an issue there, but...)
in conclusion: Some files will be more than 5 times slower when using FFS synchronization across disks.
viewtopic.php?t=10221
(Didn't mention what "some files" might have been. Maybe they were multiple thousands of thumbnail's of his .mp4 files ;-).)
viewtopic.php?t=10375
(Former default, latter not. Wouldn't expect an issue there, but...)
in conclusion: Some files will be more than 5 times slower when using FFS synchronization across disks.
viewtopic.php?t=10221
(Didn't mention what "some files" might have been. Maybe they were multiple thousands of thumbnail's of his .mp4 files ;-).)
- Posts: 8
- Joined: 17 Jun 2025
Thanks for the replies and thanks @therube for posting those links - I will look and see what those settings are configured to in the transfer job. I have been away from my workstation but I will have a look tomorrow at the discussed options. It's interesting to me that those other forums stated that the issues started after an update - I share a similar experience as this exact sync job as been running for about 5 years with no issue. I run it every quarter or so (sometimes not even... easy to slip the mind). Perhaps the symptoms are related?
Regarding different workflows - I've already stated that this job completes normally as long as the thumbnail folder is either exempted or already in sync. Again, there were no errors thrown and the sync does complete... eventually. I'll do a few more experiments for fun and see what I can find out.
Regarding different workflows - I've already stated that this job completes normally as long as the thumbnail folder is either exempted or already in sync. Again, there were no errors thrown and the sync does complete... eventually. I'll do a few more experiments for fun and see what I can find out.
- Posts: 8
- Joined: 17 Jun 2025
Hi, so a few observations:
The initial sync job did NOT have the database option checked for UPDATE.
The global option fail-safe copy is ENABLED.
For fun, I ran the sync job with the global option of fail-safe copy OFF. The result was pretty much the same.14 minutes to transfer 7.23MB of data, with about 10% of that being thumbnails.
I suspect it's either the way android presents "hidden" information or the way FFS handles folders with many many items in them.
THAT BEING SAID.
I ran a similar job for my pixel 9 pro. Same PC, similar job, but as this phone is much much newer (I've been using it about 3 months) its thumbnail folder is way smaller. It completes the sync job quite quickly, not getting hung up on the thumbnail folder. Interesting!!
Anyways, this is getting pretty long in the tooth but something is definitely going on. My next step is to do a complete backup on my samsung s20 fe with adb just to confirm that the connection and phone are operating correctly. If a client is requiring a "full" android backup (without root) I've had good success with a typical adb rsync style job.
The initial sync job did NOT have the database option checked for UPDATE.
The global option fail-safe copy is ENABLED.
For fun, I ran the sync job with the global option of fail-safe copy OFF. The result was pretty much the same.14 minutes to transfer 7.23MB of data, with about 10% of that being thumbnails.
I suspect it's either the way android presents "hidden" information or the way FFS handles folders with many many items in them.
THAT BEING SAID.
I ran a similar job for my pixel 9 pro. Same PC, similar job, but as this phone is much much newer (I've been using it about 3 months) its thumbnail folder is way smaller. It completes the sync job quite quickly, not getting hung up on the thumbnail folder. Interesting!!
Anyways, this is getting pretty long in the tooth but something is definitely going on. My next step is to do a complete backup on my samsung s20 fe with adb just to confirm that the connection and phone are operating correctly. If a client is requiring a "full" android backup (without root) I've had good success with a typical adb rsync style job.
- Posts: 1
- Joined: 4 Jan 2026
- AudioWithoutThumb.png (61.37 KiB) Viewed 1501 times
I encountered the same slow situation when copying the recording (without any thumbnails), which told me it would take 3 hours, but the final stage suddenly sped up and finished in 13 minutes.
- Posts: 1
- Joined: 2 Feb 2026
I have the same problem. It seems to be device independent. Same issue on both Google Pixel 4 XL and Google Pixel 10 Pro XL. The Problem is also not related specifically to thumbnails. It appears with large numbers of small files. Compare is very fast although it has to processs almost 50.000 files. But Sync is then extremely slow with just 50 kb/s or even less. Using the newest version 14.6. Fail-safe copy on or off does not make a difference. More than one thread leads to "ERROR_BUSY" on the MTP side. Transfer with Windows Explorer is way faster.
