# Cannot open MP4s to change tag data

**URL:** https://community.mp3tag.de/t/cannot-open-mp4s-to-change-tag-data/44896
**Category:** Support
**Created:** [March 19, 2019, 2:23am UTC](https://community.mp3tag.de/t/cannot-open-mp4s-to-change-tag-data/44896 "2019-03-19T02:23:37Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![JAMotter](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/j/ac91a4/32.png) [@JAMotter](https://community.mp3tag.de/u/JAMotter)
#### Post date: [March 19, 2019, 2:23am UTC](https://community.mp3tag.de/t/cannot-open-mp4s-to-change-tag-data/44896/1 "2019-03-19T02:23:37Z")

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I have several thousand MP4 video files of segments of lectures, perhaps 100 different lectures. I am trying to edit the tag information to add disc number and track number. Of the 2,500 different MP4s, 99% worked. But about 35 did not work. The MP3Tag app said they could not be opened. They were randomly dispersed across the various courses, so I am not sure what is wrong with them, nor how to fix the problem. The videos seem to work fine, I just can’t edit the tag data.

Does anyone have any suggestions?

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### Author: ![ohrenkino](https://community.mp3tag.de/user_avatar/community.mp3tag.de/ohrenkino/32/4843_2.png) [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [March 19, 2019, 6:15am UTC](https://community.mp3tag.de/t/cannot-open-mp4s-to-change-tag-data/44896/2 "2019-03-19T06:15:23Z")

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> [@JAMotter](#):
>
> Does anyone have any suggestions?

I found this thread:

> [@Tags not saved in mp4 files](https://community.mp3tag.de/t/tags-not-saved-in-mp4-files/14151):
>
> I'm trying to add titles, album, artist tags to a set of mp4 files. No error shows up when I tell it to save the tags, but the files do not have any tags in them. As a result this software seems totally useless. What am I doing wrong? I've tried several versions of mp3tag including 2.53 with no change in behavior. I don't see any way to make it work and there is no documentation pointing me to what I'm doing wrong.

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### Author: ![system](https://community.mp3tag.de/uploads/default/original/2X/c/ce7035d426cb755a7916793326d23b465222a407.png) [@system](https://community.mp3tag.de/u/system)
#### Post date: [February 9, 2026, 12:27pm UTC](https://community.mp3tag.de/t/cannot-open-mp4s-to-change-tag-data/44896/3 "2026-02-09T12:27:59Z")

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