# Unable to Sync (force sync required) (Unknown response code: 400)

**URL:** <https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383>\
**Category:** Syncing & AnkiWeb\
**Created:** [November 28, 2021, 4:48pm UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383 "2021-11-28T16:48:05Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![drkasnight](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@drkasnight](https://forums.ankiweb.net/u/drkasnight)\
**Post date:** [November 28, 2021, 4:48pm UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/1 "2021-11-28T16:48:05Z")

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Since yesterday I have been having to force sync every time. I know you guys changed the database and said it would fix itself once you do the force sync but it hasn’t.

 ![Screen Shot 2021-11-28 at 11.46.45 AM](https://us1.discourse-cdn.com/flex002/uploads/anki2/original/2X/6/6d5f523bf3f8f9101f73b237d325d62db6563216.png)

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**Author:** ![dae](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/dae/32/65_2.png) [@dae](https://forums.ankiweb.net/u/dae)\
**Post date:** [November 29, 2021, 12:55am UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/2 "2021-11-29T00:55:27Z")

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You’re using quite an old Anki version on your computer. If you update to a more recent version, can you reproduce the issue after doing another full sync?

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**Author:** ![drkasnight](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@drkasnight](https://forums.ankiweb.net/u/drkasnight)\
**Post date:** [November 29, 2021, 10:51am UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/3 "2021-11-29T10:51:26Z")

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Looks like updating was the trick. Thanks!

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**Author:** ![ar321](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@ar321](https://forums.ankiweb.net/u/ar321)\
**Post date:** [November 30, 2021, 12:48pm UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/4 "2021-11-30T12:48:46Z")

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I’m having a similar issue but my computer software won’t let me update to the newer version  
Is there anyway to solve this without updating?

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**Author:** ![dae](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/dae/32/65_2.png) [@dae](https://forums.ankiweb.net/u/dae)\
**Post date:** [December 2, 2021, 5:27am UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/5 "2021-12-02T05:27:47Z")

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You could start by trying 2.1.35-alternate, which should work on your old macOS version. If that doesn’t help, you might want to consider updating to macOS 10.13 - as far as I’m aware, it should work on Macs that support 10.12.

> **[How to get old versions of macOS](https://support.apple.com/en-au/HT211683)**
>
> If your Mac isn't compatible with the latest macOS, you might be able to upgrade to an earlier macOS, such as macOS Big Sur, Catalina, Mojave or High Sierra.

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**Author:** ![system](https://us1.discourse-cdn.com/flex002/uploads/anki2/original/1X/8f1279ababc5879d54e4838989f606cfe55af8c7.jpeg) [@system](https://forums.ankiweb.net/u/system)\
**Post date:** [May 1, 2023, 6:14am UTC](https://forums.ankiweb.net/t/unable-to-sync-force-sync-required-unknown-response-code-400/15383/6 "2023-05-01T06:14:44Z")

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Closed on May 1, 2023, 6:14am UTC