{"version":"2.1.299","anchor":"linux-sandbox-deny-placeholders-and-file-masks-reworked","canonical_anchor":"linux-sandbox-deny-placeholders-and-file-masks-reworked","heading":"Linux sandbox handles blocked paths that do not exist more carefully","tier":"notice","area":"Sandbox","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299\/e\/linux-sandbox-deny-placeholders-and-file-masks-reworked","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299","markdown":"### Linux sandbox handles blocked paths that do not exist more carefully\n\nOn Linux, the sandbox no longer always sets up a placeholder for a missing blocked path, and file masks now win over read blocks\n\n**What**\n\nOn Linux, Claude Code can run commands inside a sandbox, a fenced-off space that limits which files a command can see or change. It is built with a tool called bubblewrap. The way the sandbox handles paths you have blocked has changed:\n\n- Paths blocked from reading are now matched exactly as written.\n\n- A blocked path that does not exist gets a placeholder only when one can be created. Otherwise Claude Code logs \"No placeholder for\" that path. Before, a placeholder was always mounted there.\n\n- File masks now take precedence over read blocks. A read block at a spot a file mask already covers is skipped.\n\n- Setting up the sandbox now stops with an error if the sandbox settings change while blocked paths are being worked out.\n\n**Why**\n\nThis fixes cases where the sandbox failed to start because a blocked path sat in a folder that could not be written to.\n\n- Area: Sandbox\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}