# LlamaIndex Memory drops your priority=1 memory block first

*Disclosure: I work on MemorySync (I'm Mohammed, the founder). I drafted this page with AI assistance and checked it against the source issue, the linked PR and the MemorySync LlamaIndex guide on Oct 28, 2026. I didn't run any code for this page.*

## The question

[run-llama/llama_index#23090](https://github.com/run-llama/llama_index/issues/23090) reports that when memory blocks plus short-term chat history exceed `token_limit`, `Memory._truncate_memory_blocks` drops blocks in ascending priority order. So the block with `priority=1` (documented as highest priority) is truncated first, and `priority=2` survives. With the docs' own example (`FactExtractionMemoryBlock` at 1, `VectorMemoryBlock` at 2), condensed facts go before bulk retrieval.

**Status (checked 2026-10-28):** open, 3 comments. A commenter pointed to PR #23093 ("fix(core): truncate lowest-priority memory blocks first"), but that PR is now closed without being merged, so no fix has landed as far as the issue shows.

## Workarounds

*Not run for this page; the issue includes a short repro you can run against your installed version first.*

- **Use** `priority=0` **for the block you can't lose.** Per the field's docs, 0 means never truncate; the issue doesn't report that being broken.
- **Raise** `token_limit` **or shrink blocks** so truncation doesn't trigger in normal conversations.
- **Don't rely on the 1-vs-2 order** until a fix ships. If you must, test which block survives on your version with the issue's repro and set priorities to match the observed behaviour, then re-check after upgrades.

## Common questions

**Is there a fix?** Not as of Oct 28, 2026: the issue is open, and PR #23093 was closed without being merged.

**Which priority is safe?**`priority=0`, documented as never truncated. The issue doesn't report that being broken.

## Where MemorySync fits

Only if you use it already or are evaluating it. The [MemorySync LlamaIndex guide](https://docs.memorysync.io/guides/llamaindex?utm_source=hashnode&utm_medium=organic_page&utm_campaign=v5_oct25&utm_content=pseo_llamaindex-memory-block-priority-truncation) documents a `MemorySyncMemoryBlock` whose `atruncate` drops its lowest-ranked lines instead of the whole block. That changes what happens to that one block when it's truncated; it doesn't fix the order bug in `Memory` itself. To see save and recall in your browser first, try the [MemorySync playground](https://memorysync.io/?utm_source=hashnode&utm_medium=organic_page&utm_campaign=v5_oct25&utm_content=pseo_llamaindex-memory-block-priority-truncation). Founding offer: use code FOUNDING30 for 30% off Starter for your first 3 months (Settings → Billing).

## Sources

- run-llama/llama_index#23090, "\[Bug\]: Memory truncates highest-priority memory blocks first" (read 2026-10-28)
- run-llama/llama_index PR #23093 (closed, not merged; read 2026-10-28)
- MemorySync LlamaIndex guide: [docs.memorysync.io/guides/llamaindex](http://docs.memorysync.io/guides/llamaindex)

Founding offer: use code FOUNDING30 for 30% off Starter for your first 3 months (Settings → Billing).