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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"bug: invalid replacement userId tears down current SDK user state","articleBody":"### Issue Summary\n\n\n```text\nbug: invalid replacement userId tears down current SDK user state\n```\n\n\n```md\n## Issue\n\n`setUserId` currently tears down the existing SDK user state before validating the replacement `userId` length.\n\nThis means an invalid oversized replacement `userId` can clear the current valid user even though the new value is rejected.\n\n## Reproduction\n\nCurrent order in `packages/js-core/src/lib/user/user.ts`:\n\n```ts\nif (currentUserId) {\n  tearDown();\n}\n\nconst MAX_USER_ID_LENGTH = 255;\nif (userId.length \u003e MAX_USER_ID_LENGTH) {\n  return okVoid();\n}\n```\n\nExample flow:\n\n```ts\nawait formbricks.setUserId(\"existing-user\");\nawait formbricks.setUserId(\"a\".repeat(256));\n```\n\n## Current behavior\n\n- Existing user state is torn down.\n- The oversized replacement `userId` is rejected.\n- No new user is set.\n- The SDK loses the previously valid user state.\n\n## Expected behavior\n\nThe replacement `userId` should be validated before tearing down the current user.\n\nIf the new `userId` is invalid, the SDK should reject it without clearing the existing valid user state.\n\n## Minimal fix\n\nMove the max-length validation before the `tearDown()` call.\n\nI verified this with a focused regression test:\n\n```bash\nvitest run src/lib/user/tests/user.test.ts\n```\n\nResult after fix:\n\n```text\n1 file passed, 7 tests passed\n```\n\nFocused ESLint also passes for:\n\n```bash\neslint src/lib/user/user.ts src/lib/user/tests/user.test.ts\n```\n\nBranch:\nhttps://github.com/bharathkumar39293/formbricks/tree/fix/sdk-setuserid-validate-before-teardown\n\nSince PR creation is restricted, I’m happy to open a PR if access is enabled, or a maintainer can cherry-pick the commit if preferred.\n```\n\n### Expected Behavior\n\n_No response_\n\n### Other information (incl. screenshots, Formbricks version, steps to reproduce,...)\n\n_No response_\n\n### Your Environment\n\nNone","author":{"url":"https://github.com/bharathkumar39293","@type":"Person","name":"bharathkumar39293"},"datePublished":"2026-06-16T05:43:51.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/8288/formbricks/issues/8288"}