# Xtrabackup : error writng file '\<unopen fd\>'

**URL:** <https://forums.percona.com/t/xtrabackup-error-writng-file-unopen-fd/21386>\
**Category:** Percona XtraBackup\
**Tags:** mysql, percona\
**Created:** [April 13, 2023, 10:49am UTC](https://forums.percona.com/t/xtrabackup-error-writng-file-unopen-fd/21386 "2023-04-13T10:49:01Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![chrisfangjl](https://avatars.discourse-cdn.com/v4/letter/c/8491ac/32.png) [@chrisfangjl](https://forums.percona.com/u/chrisfangjl)\
**Post date:** [April 13, 2023, 10:49am UTC](https://forums.percona.com/t/xtrabackup-error-writng-file-unopen-fd/21386/1 "2023-04-13T10:49:01Z")

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hello, Please tell me what is the cause of this problem…  
xtrabackup 8.0.26  
mysql 8.0.25

```auto
xtrabackup : error writng file '<unopen fd>'
xtrabackup Error : failed to write meta info pdosswms/ott_nbr_compare_result.ibd
xtrabackup error : failed to initialize page write filter
xtrabackup Error : xtrabackup_copy_datafile() failed
xtrabackup error : failed to copy datafile

```

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**Author:** ![Abhinav\_Gupta](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/abhinav_gupta/32/6262_2.png) [@Abhinav\_Gupta](https://forums.percona.com/u/Abhinav_Gupta)\
**Post date:** [April 13, 2023, 1:38pm UTC](https://forums.percona.com/t/xtrabackup-error-writng-file-unopen-fd/21386/2 "2023-04-13T13:38:32Z")

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@chrisfangjl Are you performing a full backup or an incremental backup? Could you please share more or the complete log from the output?

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<div class="post-metadata">

**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\
**Post date:** [April 13, 2023, 9:09pm UTC](https://forums.percona.com/t/xtrabackup-error-writng-file-unopen-fd/21386/3 "2023-04-13T21:09:56Z")

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@chrisfangjl Please provide the entire command you are using. Also, your PXB and MySQL versions should match exactly for best results. Are you running PXB as root? You need to do so in order to read the datafiles.