Caught ActiveRecord::StatementInvalid: SQLite3::SQLException: SQL logic error or missing database: INSERT INTO (snip)

SQLite3 を ActiveRecord で操作した場合に以下のエラーが発生しました。

Caught ActiveRecord::StatementInvalid: SQLite3::SQLException: SQL logic error
or missing database: SQL
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract_adapter.rb:150:in
`log'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/sqlite_adapter.rb:132:in
`execute'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/sqlite_adapter.rb:345:in
`catch_schema_changes'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/sqlite_adapter.rb:132:in
`execute'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/database_statements.rb:156:in
`insert_sql'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/sqlite_adapter.rb:146:in
`insert_sql'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract/database_statements.rb:44:in
`insert_without_quer

原因は、SQLite3ファイルのカレントディレクトリのパーミッションが書き込み不可になっていたためでした。
データの読み込み(SELECT)は成功していたからなかなか気づけませんでした。