---
title: "NCG Android SDK 2.19.1"
description: "Fixed a native crash (SIGSEGV / double-free) in NcgEpubFile that could occur when the same content was rapidly reopened in a multi-threaded…"
---
> For the complete documentation index, see [llms.txt](/llms.txt).

**Bug Fix**

- Fixed a native crash (SIGSEGV / double-free) in `NcgEpubFile` that could occur when the same content was rapidly reopened in a multi-threaded environment; `close()` and `release()` are now synchronized to prevent concurrent access to the native file handle.


**Changes**

- `NcgEpubFile.close()` now fully releases the native file context on each call; crypto objects remain cached at the native layer, so reopening the same CID stays fast with no performance impact.

- `NcgEpubFile.release()` now resets internal license and header state, ensuring proper license re-validation when a different CID is opened on the same instance.

- Updated Javadoc for `NcgEpubFile` (`createNcgEpub()`, `open()`, `close()`, `release()`) to document the correct lifecycle and one-instance-per-CID usage rule.