Common Event Error Causes and Solutions


SummaryA listing of common event error causes and straightforward solutions for them.

The Notifications pane in the Alooma Dashboard and the email digests clearly describe the reason for each event’s error. Clicking on a notification expands it to show additional details.


Some event issues in the Restream Queue can be handled inside Alooma, such as changing the code in the Code Engine, changing your mapping in the Mapper, or updating the data destination access credentials. Other event errors must be handled outside of Alooma, such as a table having been dropped from your data destination or a data warehouse that is offline.

Here are some common reasons your events may be sent to the Restream Queue and their solutions:

  • New Event Type Needs Mapping – Occurs when a new event type has reached the mapper, either because you connected a new input or a new event type was created in the Code Engine. You'll need to go to the Mapper and map this event type.

  • Copy Failure Error – Loading error to the data destination. For example, temporary database connection failure or changed access credentials. You may need to reconfigure Alooma’s data warehouse access configuration.Overview

  • Type Conversion Error – The type of data in the event doesn’t match the column type to which the event is mapped. For example, when an event field arrives with a string value in a field that is mapped to an integer in the data destination or when an event field value is too long. You may need to change the mapping in the Mapper.

  • Out-of-Range Error – This type of error generally occurs when the value of a field is out of range of the data type that field is mapped to, such as a small number appearing in a field which is mapped to timestamp, and that number is too small to be considered a timestamp as seconds from epoch. Fix this by modifying the value or discarding the event in the Code Engine.

  • Varchar Value Too Long – This occurs when the value of a field that is mapped to a varchar type of a particular length arrives as longer than the allowed length of the varchar. This is another type of "out-of-range", but specifically for varchar lengths. You can fix this by modifying or truncating the field value in the Code Engine, or choosing the "Truncate" option in the data type drop-down in the Mapper.

    Redshift users: you can change the length of a varchar field directly in the Mapper UI. See Altering a Column via the Mapper.

  • Transform Function Error – Events that trigger an error in the code that you wrote in Alooma’s Code Engine. For example, if your code assumes that a specific field exists in an event, and it doesn’t. You may need to sample an event of this error type and modify your code accordingly in the Code Engine.

  • Unmapped Event Fields – Alooma lets you configure how strictly to handle new incoming event fields (meaning schema changes). According to your configuration, Alooma can be:

    • Strict – Automatically sends each event that contains an unmapped field to the Restream Queue.

    • Flexible – Each unmapped field of an event is discarded (ignored) and the rest of the event is handled according to the defined mapping.

    • Auto-mapping – Automatically maps event field changes and loads these events to the data destination.

  • Mapping Error (low surrogate) – This can occur if the data you are processing contains certain UTF-16 characters. See Code Engine Common Tasks for an example of how to strip or replace those characters.


A sudden increase of events in the Restream Queue may indicate the source of the error, such as a Code Engine change, inputting a bad batch of events and so on. Keeping the Restream Queue less than 50% full may prevent it from overflowing, and keeps restreaming times short.

If you have questions or need help resolving any events in the Restream Queue, feel free to contact us anytime.

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