# Backup fails with "stream was too long"

**URL:** <https://forum.duplicati.com/t/backup-fails-with-stream-was-too-long/19846>\
**Category:** Support\
**Tags:** performance, canary\
**Created:** [January 5, 2025, 6:15am UTC](https://forum.duplicati.com/t/backup-fails-with-stream-was-too-long/19846 "2025-01-05T06:15:21Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![kenkendk](https://forum.duplicati.com/user_avatar/forum.duplicati.com/kenkendk/32/5305_2.png) [@kenkendk](https://forum.duplicati.com/u/kenkendk)\
**Post date:** [January 6, 2025, 3:35pm UTC](https://forum.duplicati.com/t/backup-fails-with-stream-was-too-long/19846/8 "2025-01-06T15:35:48Z")

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> [@FreaQ](#):
>
> You mean dblock size?

No 🙂  
`dblock` is usually either 100KiB or 1MiB. If you have 4GiB dblock, it means you will look for deduplications on blocks larger than 4GiB? That requires volumes larger than 4GiB then…

> [@FreaQ](#):
>
> But this means, I need to start the backup from scratch because changing dblock size to an existing backup is not possible.

True, if it really is `dblock` and not `volume size`, then it cannot be changed.

> [@FreaQ](#):
>
> Just to clarify: Is this an issue on Jottaclouds side or duplicati?

It is Duplicati doing the wrong thing here, buffering the entire request in memory.

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