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Help with production error: "😿‼️ Error when syncing subscriber attributes. Details: The operation couldn’t be completed. (RevenueCat.BackendError error 0.) UserInfo: [:]"


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Hi,
We added the RevenueCat react-native SDK to our app in the last release and we are seeing thousands of these errors across thousands of users: “😿‼️ Error when syncing subscriber attributes. Details: The operation couldn’t be completed. (RevenueCat.BackendError error 0.) UserInfo: [:]”. They seem to happen immediately after app launch and SDK initialization. 

What is the cause of this and how do I fix it? 

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4 replies

joan-cardona
RevenueCat Staff
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  • RevenueCat Staff
  • 489 replies
  • July 10, 2025

Hi ​@Jacob from Deglaze,

Which attributes are you settings in your app and at which point in the app lifecycle are you doing it?

It’s important to not perform any action (like setting attributes) before configuring correctly the SDK.

Best,


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Thanks ​@joan-cardona. I know the SDK is initialized because a different error is produced when that is not the case  - I just verified this locally. 

Here is our call sequence:

  1. Purchases.configure on app startup.
  2. When a user signs in and Purchases.getAppUserID() does not match the user ID:
    1. Purchases.collectDeviceIdentifiers()
    2. Purchases.setAttributes with a few custom attributes and 3 reserved attributes. We know this call works most of the time because we see the values in the dashboard. i.e. I don’t think there’s anything wrong with this code as the values are all set to a fixed-length string
    3. Purchases.logIn 
    4. Purchases.syncAttributesAndOfferingsIfNeeded() for good measure, as we weren’t always seeing the attributes synced when calling login. 

 


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  • RevenueCat Staff
  • 624 replies
  • July 18, 2025

Hi ​@Jacob from Deglaze thank you for this information!

Purchases.setAttributes with a few custom attributes and 3 reserved attributes. We know this call works most of the time because we see the values in the dashboard. i.e. I don’t think there’s anything wrong with this code as the values are all set to a fixed-length string

Could you please set your log level to verbose and share the entirety of the debug logs with us as there could be more information in the logs that might help us see what is happening here? I recommend opening a support ticket to share these to not share any sensitive information on this forum, and if you could also share the code blocks mentioned in this sequence that would be great! You can open a ticket here

 

Purchases.syncAttributesAndOfferingsIfNeeded() for good measure, as we weren’t always seeing the attributes synced when calling login. 

Calling logIn() should sync attributes but there could be a slight delay. Calling the syncAttributesAndOfferingsIfNeeded() method will explicitly sync attributes mid-session so it is fine to call this after logIn() to force the sync.


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Hi ​@Haley Pace, thanks for the reply. I did end up opening a support ticket. We don’t really want to turn on verbose logs in our production environment.

I have asked this in the support email chain as well, but for future readers, it might be helpful if you could share the significance of the empty map and error code 0 in the log. 


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