TYPO3 Core

The message "illegal mix of collations" is shown if the BE Modul Webreactions or Webhooks is installed.

Because both modules creates a db table with a field using a differente collation:

sys_reaction.fields use the collation utf8mb4_bin and sys_webhook.additional_headers use the collation utf8mb4_bin also

But the default collation is "utf8mb4_unicode_ci"

This results in a error message inside the BE Reports Module:

our default database is set to create tables with character set "utf8mb4_unicode_ci", but contains tables or columns with different collations. Please fix these tables to avoid "illegal mix of collations" errors.

i dont have taken a deeper look if the different collation is necessary for the db fields (imho sorting and comparing) but this message is maybe a false positive or could be confusing some users