# AUR0778 **Note:** This error code does not appear to be actively used in the current version of the `runtime-html` package. This documentation is based on the error message string and may not reflect an actual runtime scenario. ## Error Message `AUR0778: Unsupported: [repeat] cannot count ` Where `` is the string representation of the value whose count could not be determined. ## Description This error likely indicates an internal state issue within the `repeat` controller where it attempted to determine the size or length of the collection being iterated over, but the collection was in a state or of a type where its count could not be retrieved (e.g., lacking a `length` or `size` property). ## Cause (Speculative, as the error is not currently thrown) This might have occurred if the repeater's internal logic expected a collection with a countable property (like `.length` for Arrays/strings or `.size` for Maps/Sets) but encountered an unusual iterable or state where this property was missing or inaccessible. ## Solution (Speculative) * Ensure the collection bound to `repeat.for` consistently maintains its expected type (Array, Map, Set, string, number). * If using custom iterables, ensure they behave predictably and don't enter states where their conceptual "size" cannot be determined if required by internal repeater logic. * Given this error isn't currently thrown, if you encounter it, it might indicate a bug in the version of Aurelia being used or an interaction with unusual custom elements/attributes. Report it as an issue with detailed reproduction steps. ## Example (N/A - Cannot provide a specific example as the error is not actively thrown) ## Debugging Tips * Verify the collection bound to `repeat.for` is a standard, supported type. * Check for any custom logic or integrations that might interfere with the repeater's handling of the collection. * If this error appears unexpectedly, consider filing a bug report with Aurelia. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.aurelia.io/developer-guides/error-messages/runtime-html/aur0778.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.