I just stumbled accross a problem when I wanted to analyze the database structure in my Typo3 Install Tool. It won't stop loading. When I took a look in the browser developer tools I found an error from the server response: Uncaught (in promise) SyntaxError: Unexpected token '{', "f{"success""... is not valid JSON It seems that an "f" is placed in front in the JSON response. And I have no idea where this is coming from. It's not just the "Analyze Database Structure" it's also in "Remove Temporary Assets" and "Flush TYPO3 and PHP Cache". For example the response for "Flush TYPO3 and PHP Cache" is:
f{
"success": true,
"status": [
{
"severity": 0,
"title": "Caches cleared",
"message": "Successfully cleared all caches and all available opcode caches.",
"storeInSession": false
}
]
}
Is this a bug in Typo3? I found nothing over google. I'm using Version 11.5.32.
To me this sounds as if you might have accidentally edited a file and added a "f" anyhwere before the first <?php tag?
Also check your custom code. Ensure your vendor/ or symlinked typo3-sources directory is untouched and contains no modifications. If it still happens, temporarily disable all extensions and see which one may cause it.
HTH!