DBD::SQLite::db prepare_cached failed: near "?": syntax error at...

You're getting the error because placeholders can only replace values, not field names, table names, SQL clauses, etc.

my $sth = $dbh->prepare("
   UPDATE twsJobs
      SET ? = ?
    WHERE jobId = ?
");
$dbh->execute($field_name, ..., ...);
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should be

my $q_field = $dbh->quote_identifier($field_name);
my $sth = $dbh->prepare("
   UPDATE twsJobs
      SET $q_field = ?
    WHERE jobId = ?
");
$dbh->execute(..., ...);
[download]