# Mp3tag cannot write to mp4 files
**URL:** https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278
**Category:** Support
**Created:** [April 21, 2025, 12:40pm UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278 "2025-04-21T12:40:56Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Manolo](https://community.mp3tag.de/u/Manolo)
#### Post date: [April 21, 2025, 12:40pm UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/1 "2025-04-21T12:40:56Z")
mp3tag won't let me change the tags on my MP4 files.
I get an error message saying "Cannot write to file..."
---
### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [April 21, 2025, 12:50pm UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/2 "2025-04-21T12:50:21Z")
See e.g. here:
> [@MP4 files cannot be opened for writing](https://community.mp3tag.de/t/mp4-files-cannot-be-opened-for-writing/49164):
>
> I thought I read that mp3tag works for editing tags on mp4 files. But, I'm getting an error message when adding a new thumbnail to an mp4 video, and it won't allow me to save it.
---
### Author:  [@chpross](https://community.mp3tag.de/u/chpross)
#### Post date: [May 3, 2025, 3:12am UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/3 "2025-05-03T03:12:16Z")
Hey,
well, i have the same problem, since version 3.29, I have to reencode all of my .m4b files to work, I am converting the capters from quick time to nero, this fixes the problem. In the log, I can see the following:
```auto
================================================================================
Mp3tag v3.29 - 03.05.2025 - 04:33:42
--------------------------------------------------------------------------------
OS-Version: Windows 11 (build 22631), 64-bit
--------------------------------------------------------------------------------
Build: Mar 28 2025 13:54:50 (64-bit)
--------------------------------------------------------------------------------
AppPath: 724.526.596.096 Bytes frei (C:\Program Files\Mp3tag\)
DataPath: 724.526.596.096 Bytes frei (C:\Users\chpro\AppData\Roaming\Mp3tag\data\)
TempPath: 724.526.596.096 Bytes frei (C:\Users\chpro\AppData\Local\Temp\Mp3tag v3.29\)
================================================================================
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt).m4b is reported as 1299920112 from the system (it's more than 1GB)
0000B02C at 0:03.093832
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 02 - Der Maertyrer (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 02 - Der Maertyrer (Ungekuerzt).m4b is reported as 1677987783 from the system (it's more than 1GB)
0000B02C at 0:03.093892
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 03 - Der Verraeter (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 03 - Der Verraeter (Ungekuerzt).m4b is reported as 2398459105 from the system (it's more than 1GB)
0000B02C at 0:03.093922
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Jens Forwick - Die Kalandaha Chroniken 06 - Builder (Ungekuerzt).part1\Jens Forwick - Die Kalandaha Chroniken 06 - Builder (Ungekuerzt).part1.m4b is reported as 1172021342 from the system (it's more than 1GB)
0000B02C at 0:03.093959
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Jens Forwick - Die Kalandaha Chroniken 07 - Dealbreaker (Ungekuerzt).part1\Jens Forwick - Die Kalandaha Chroniken 07 - Dealbreaker (Ungekuerzt).part1.m4b is reported as 1094450990 from the system (it's more than 1GB)
0000B02C at 0:03.093985
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Marc Elsberg - Der Fall des Praesidenten (Ungekuerzt)\Marc Elsberg - Der Fall des Praesidenten (Ungekuerzt).m4b is reported as 1577303594 from the system (it's more than 1GB)
0000B02C at 0:03.094012
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Perry Rhodan - Silber Edition - Folge 169 - Imago.part1\Perry Rhodan - Silber Edition - Folge 169 - Imago.part1.m4b is reported as 1380501933 from the system (it's more than 1GB)
0000B02C at 0:03.094042
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file E:\Audio\temp\untagged\Sean Oswald - Willkommen im Multiversum 03 - Kollaps (Ungekuerzt).part1\Sean Oswald - Willkommen im Multiversum 03 - Kollaps (Ungekuerzt).part1.m4b is reported as 1841060574 from the system (it's more than 1GB)
0000B02C at 0:03.094118
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\_audio\smp4file.cpp
Line: 589
Message: write: Manipulation of MP4 QT chapters is not supported, please remux the file to another format (E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt).m4b)
000035EC at 0:22.212697
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\_audio\smp4file.cpp
Line: 589
Message: write: Manipulation of MP4 QT chapters is not supported, please remux the file to another format (E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 01 - Der Paria (Ungekuerzt).m4b)
00009F58 at 0:30.205332
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\_audio\smp4file.cpp
Line: 589
Message: write: Manipulation of MP4 QT chapters is not supported, please remux the file to another format (E:\Audio\temp\untagged\Anthony Ryan - Der staehlerne Bund 02 - Der Maertyrer (Ungekuerzt)\Anthony Ryan - Der staehlerne Bund 02 - Der Maertyrer (Ungekuerzt).m4b)
000002C4 at 0:37.938955
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\_audio\smp4file.cpp
Line: 589
Message: write: Manipulation of MP4 QT chapters is not supported, please remux the file to another format (E:\Audio\temp\untagged\David Baldacci - Memory Man 04 - Downfall (Ungekuerzt).part1\David Baldacci - Memory Man 04 - Downfall (Ungekuerzt).part1.m4b)
0000AC5C at 1:55.094348
```
---
### Author:  [@SummerTime](https://community.mp3tag.de/u/SummerTime)
#### Post date: [May 24, 2025, 10:58pm UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/4 "2025-05-24T22:58:32Z")
Same error for me, downgrading from 3.29 to 3.28 solved the issue.
```auto
================================================================================
Mp3tag v3.29 - 24.05.2025 - 23:43:24
--------------------------------------------------------------------------------
OS-Version: Windows 10 (build 19045), 64-bit
--------------------------------------------------------------------------------
Build: Mar 28 2025 13:54:50 (64-bit)
--------------------------------------------------------------------------------
AppPath: 14.452.219.904 Bytes frei (C:\Program Files\Mp3tag\)
DataPath: 14.452.219.904 Bytes frei (C:\Users\root\AppData\Roaming\Mp3tag\data\)
TempPath: 14.452.219.904 Bytes frei (C:\Users\root\AppData\Local\Temp\Mp3tag v3.29\)
================================================================================
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\mp3tag\mtmainframeupdatehandlers.cpp
Line: 108
Message: Size of file Z:\Downloads\Audiobooks Processor\auto-m4b\untagged\Les Misérables [Christine Donougher] [Adeel Akhtar, Natalie Simpson, Adrian Scarborough, Emma Fielding, John Owen-Jones]\Les Misérables Penguin Classics.m4b is reported as 1877173972 from the system (it's more than 1GB)
000008E4 at 0:01.868833
--------------------------------------------------------------------------------
MESSAGE
--------------------------------------------------------------------------------
File: y:\projects\_audio\smp4file.cpp
Line: 589
Message: write: Manipulation of MP4 QT chapters is not supported, please remux the file to another format (Z:\Downloads\Audiobooks Processor\auto-m4b\untagged\From Eternity to Here - The Quest for the Ultimate Theory of Time\From Eternity to Here - The Quest for the Ultimate Theory of Time.m4b)
000012F8 at 1:48.781188
```
---
### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [May 29, 2025, 11:28am UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/5 "2025-05-29T11:28:23Z")
I've just released [Mp3tag v3.30](https://community.mp3tag.de/t/455) and relaxed this recent change that prevents retagging of MP4 files with \> 255 QT chapters to not take effect if the global tag is changed (and not the individual chapters).
---
### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [June 28, 2025, 11:29am UTC](https://community.mp3tag.de/t/mp3tag-cannot-write-to-mp4-files/68278/6 "2025-06-28T11:29:18Z")
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