Otter 3.2.1 fatals when loading `FSE_Onboarding` during frontend startup

Summary

Otter 3.2.1 can terminate a frontend request during plugin startup when the onboarding class cannot be loaded.

Expected behavior: Frontend requests load without requiring the onboarding class to be unavailable.

Actual behavior: Startup ends with an uncaught Class ".../FSE_Onboarding" not found fatal error.

Impact: The affected site's frontend request cannot complete while this startup path is reached.

Customer context

• Product / area: Otter Blocks startup and FSE onboarding
• Version: 3.2.1
• Environment: WordPress 7.0.2; PHP 8.4.23
• Integration / third party: Themeisle SDK 3.3.58 was present; the telemetry location is outside SDK code.
• Reported error / symptom: Uncaught FSE_Onboarding class-not-found fatal at inc/class-main.php:97.
• Impact: 3 occurrences across 1 production site in the reporting window; frontend context.

Reproduction notes

1. Install Otter Blocks 3.2.1 in a WordPress environment using PHP 8.4.23.
2. Load a frontend request so WordPress runs Otter's init callbacks.
3. Confirm whether startup reaches Main::autoload_classes() with FSE_Onboarding unavailable.

Telemetry confirms the fatal in production; an exact packaged-artifact reproduction has not been run.

Diagnosis

Conclusion

Production telemetry provides a direct frontend fatal at the new $classname() call. In the 3.2.1 tag, the loader includes ThemeIsle\GutenbergBlocks\Plugins\FSE_Onboarding in its unconditional startup list, so an unavailable autoload target terminates the request. The source class exists and Composer declares inc/ as a classmap, making the fatal evidence of a shipped/install autoload inconsistency rather than an absent source declaration.

Where this likely occurs

• inc/class-main.php — ThemeIsle\GutenbergBlocks\Main::autoload_classes() lines 66-102; 3.2.1 includes FSE_Onboarding at line 76 and directly instantiates each listed class at line 97, matching the telemetry location.
• inc/plugins/class-fse-onboarding.php — ThemeIsle\GutenbergBlocks\Plugins\FSE_Onboarding lines 8-15; the expected class declaration is present in tag v3.2.1.
• composer.json — autoload lines 61-65; the product declares inc/ as a Composer classmap and loads the Themeisle SDK bootstrap separately.
• bin/dist.sh — distribution workflow lines 26-37; the release archive is assembled from the filtered tree, after dependencies are installed by the tag deployment workflow in .github/workflows/deploy.yml lines 24-33.

Engineering notes

• The telemetry explicitly marks the location as outside Themeisle SDK code, so routing is Codeinwp/otter-blocks.
• The class was added to the loader in commit aa3e24edfadc794ef447ff3b7430f3179abb8970 and remains present in tag v3.2.1.
• FSE_Onboarding contains mainly admin/editor hooks, but it is placed in the unconditional init-time class list. The fatal therefore affects frontend bootstrap before its feature-specific hooks determine whether onboarding is used.
• The repository checkout does not contain the built vendor/ directory or the deployed ZIP, so the generated classmap and archive contents for the failing installation were not directly inspected.

Test coverage status

No relevant coverage was found during inspection. A search of tests/ found no tests covering FSE_Onboarding loading or Main::autoload_classes() with the production Composer autoloader.

What to verify or explore next

• May be worth reproducing with the exact 3.2.1 WordPress.org or product ZIP on PHP 8.4.23 and checking frontend bootstrap.
• Inspect the packaged vendor/composer/autoload_classmap.php for the FSE_Onboarding mapping and confirm that inc/plugins/class-fse-onboarding.php is in the archive.
• If the packaged mapping is present, compare enabled-plugin and autoloader interactions on the affected WordPress/PHP versions.

Unknowns / follow-up

• The telemetry report contains no full resolved class name, deployed archive hash, or installed-file inventory.
• It is unknown whether this occurred after a partial update or with an unmodified 3.2.1 distribution.

Confidence

Confidence: 88/100

Production telemetry records three frontend fatal errors on one site running Otter 3.2.1. The tagged source unconditionally instantiates FSE_Onboarding at the exact reported line, while the class is expected to be Composer-classmapped; the reported class-not-found condition therefore prevents normal frontend startup and warrants investigation of the shipped artifact/autoload state.

Crash telemetry

Occurrences	3
Distinct sites	1
First seen	2026-08-02 16:48 UTC
Last seen	2026-08-02 16:48 UTC
Crash location	product:inc/class-main.php:97
Request context	frontend
Inside Themeisle SDK	no
Product versions	3.2.1
WP versions	7.0.2
PHP versions	8.4.23
SDK versions	3.3.58

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Source: automated crash report — otter-blocks, fingerprint 2a9815a6dadd574b66ac18f7bfdc4b45
Generated by bug-report-triage (ID: bug-report-triage_6a717ffb8fd588.54732445)

Start in inc/class-main.php at Main::autoload_classes(), then inspect inc/plugins/class-fse-onboarding.php, composer.json, and bin/dist.sh. Reproduce the exact 3.2.1 package on the stated WordPress and PHP versions, checking the generated Composer classmap and archive contents. Done means the cause is confirmed and a frontend startup no longer ends in this fatal, with regression coverage identified or added.