TYPO3 Core

At install tool step 2, you are able to write a new database to create or choose a database from a select list.

If you write the name of a already existing database, the name isn't written to localconf.php and the next step will result in a error.

Solutio:
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check if written databasename exist in array of existing databases and then write it, if true.

Going to a meeting in 20 minutes, but will try to create patch later tonight!
(issue imported from #M14478)