Fatal error: Array and string offset access syntax with curly braces is no longer supported

PHP 8.0 removed the old $value{0} syntax for reading a character or an array element. Files that still use it no longer compile, so one plugin or theme with this code stops the whole site after a PHP 8 upgrade.

Common causes

References

1. Backward incompatible changes in PHP 8.0 (PHP.net)
2. Debugging in WordPress (Advanced Administration Handbook)

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White screens and fatal errors (plugin conflicts, PHP version incompatibility) are handled automatically: on a copy of your site in the recovery station, the system turns on debug mode, finds the plugin or theme causing the error and deactivates it (not deleted); a white screen caused by exhausted memory is fixed by raising the memory limit. After the fix, the home page and inner pages are re-verified, and only then is the result written back to your host (in WP admin mode, a recovered package is delivered instead). Fixes are made on a copy of your site in the recovery station and written back only after re-verification passes. In your site’s database, the protected tables (members, comments, orders and form submissions) are copied as structure only. In SSH and FTP mode, the system creates a pre-recovery backup on your host before writing back and restores from it if verification after write-back fails. If the recovery cannot be completed, the recovery fee is refunded in full.

1. Initial assessment: Site URL entry
2. Copy to the recovery station: Work on a copy
3. Diagnosis: Item-by-item checks
4. Recovery and verification: Home and inner pages
5. Write-back or delivery: Only after verification passes