A valid configuration was treated as invalid during instance startup

### To reproduce

Using docker image (image: questdb/questdb:latest) to start questdb instance.
During startup, exception came up as below:

```
Attaching to questdb
questdb  | Found /root/.questdb mount, overwriting QUESTDB_DATA_DIR
questdb  | No arguments found in the configuration, start with default arguments
questdb  | Running as root user
questdb  | Log configuration loaded from: /root/.questdb/conf/log.conf
questdb  | 2026-02-10T16:12:11.000837Z A server-main QuestDB 9.3.2. Copyright (C) 2014-2026, all rights reserved.
questdb  | 2026-02-10T16:12:11.900064Z A server-main linux-x86-64 [AVX2,8, 64 bits, 1 processors]
questdb  | 2026-02-10T16:12:11.900236Z A server-main fs.file-max checked [limit=524288]
questdb  | 2026-02-10T16:12:11.900398Z A server-main vm.max_map_count checked [limit=1048576]
questdb  | 2026-02-10T16:12:12.053505Z I server-main Web Console is up to date
questdb  | 2026-02-10T16:12:12.108558Z A server-main Server config: /root/.questdb/conf/server.conf
questdb  | io.questdb.Bootstrap$BootstrapException: io.questdb.ServerConfigurationException: Configuration issues:
questdb  |     Invalid settings (not recognized, probable typos):
questdb  |         * cairo.sql.backup.dir.datetime.format
questdb  |
questdb  |      at io.questdb@9.3.2/io.questdb.Bootstrap.<init>(Bootstrap.java:224)
questdb  |      at io.questdb@9.3.2/io.questdb.Bootstrap.<init>(Bootstrap.java:98)
questdb  |      at io.questdb@9.3.2/io.questdb.ServerMain.<init>(ServerMain.java:83)
questdb  |      at io.questdb@9.3.2/io.questdb.ServerMain.main(ServerMain.java:137)
questdb  | Caused by: io.questdb.ServerConfigurationException: Configuration issues:
questdb  |     Invalid settings (not recognized, probable typos):
questdb  |         * cairo.sql.backup.dir.datetime.format
questdb  |
questdb  |      at io.questdb@9.3.2/io.questdb.PropServerConfiguration.validateProperties(PropServerConfiguration.java:2315)
questdb  |      at io.questdb@9.3.2/io.questdb.PropServerConfiguration.<init>(PropServerConfiguration.java:808)
questdb  |      at io.questdb@9.3.2/io.questdb.DynamicPropServerConfiguration.<init>(DynamicPropServerConfiguration.java:150)
questdb  |      at io.questdb@9.3.2/io.questdb.DynamicPropServerConfiguration.<init>(DynamicPropServerConfiguration.java:186)
questdb  |      at io.questdb@9.3.2/io.questdb.PropBootstrapConfiguration.getServerConfiguration(PropBootstrapConfiguration.java:40)
questdb  |      at io.questdb@9.3.2/io.questdb.Bootstrap.<init>(Bootstrap.java:183)
questdb  |      ... 3 more
```
The instance wouldn't start. However, no issue was found when I fell back to version 9.3.1 with same configuration file.
```
Attaching to questdb
questdb  | Found /root/.questdb mount, overwriting QUESTDB_DATA_DIR
questdb  | No arguments found in the configuration, start with default arguments
questdb  | Running as root user
questdb  | Log configuration loaded from: /root/.questdb/conf/log.conf
questdb  | 2026-02-10T16:14:21.130029Z A server-main QuestDB 9.3.1. Copyright (C) 2014-2026, all rights reserved.
questdb  | 2026-02-10T16:14:21.945137Z A server-main linux-x86-64 [AVX2,8, 64 bits, 1 processors]
questdb  | 2026-02-10T16:14:21.945296Z A server-main fs.file-max checked [limit=524288]
questdb  | 2026-02-10T16:14:21.945422Z A server-main vm.max_map_count checked [limit=1048576]
questdb  | 2026-02-10T16:14:22.213556Z I server-main extracted [path=/root/.questdb/public/index.html]
questdb  | 2026-02-10T16:14:22.215591Z I server-main extracted [path=/root/.questdb/public/assets/open-sans-v13-latin-600-C1Kmc7KT.woff]
questdb  | 2026-02-10T16:14:22.217034Z I server-main extracted [path=/root/.questdb/public/assets/upload.svg]
questdb  | 2026-02-10T16:14:22.264285Z I server-main extracted [path=/root/.questdb/public/assets/index-BD25QvPt.js]
questdb  | 2026-02-10T16:14:22.309317Z I server-main extracted [path=/root/.questdb/public/assets/vs/editor/editor.main.js]
questdb  | 2026-02-10T16:14:22.314556Z I server-main extracted [path=/root/.questdb/public/assets/questdb.svg]
questdb  | 2026-02-10T16:14:22.316707Z I server-main extracted [path=/root/.questdb/public/assets/index-CASK4XST.js]
questdb  | 2026-02-10T16:14:22.319351Z I server-main extracted [path=/root/.questdb/public/assets/questdb-logotype.svg]
questdb  | 2026-02-10T16:14:22.322719Z I server-main extracted [path=/root/.questdb/public/assets/open-sans-v13-latin-300-DFA0ym50.woff]
questdb  | 2026-02-10T16:14:22.325049Z I server-main extracted [path=/root/.questdb/public/assets/favicon.ico]
questdb  | 2026-02-10T16:14:22.326368Z I server-main extracted [path=/root/.questdb/public/assets/icon-line-chart.svg]
questdb  | 2026-02-10T16:14:22.330064Z I server-main extracted [path=/root/.questdb/public/assets/icon-explain-queries.svg]
questdb  | 2026-02-10T16:14:22.331021Z I server-main extracted [path=/root/.questdb/public/assets/open-sans-v13-latin-regular-BKF8bpuc.woff]
questdb  | 2026-02-10T16:14:22.336476Z I server-main extracted [path=/root/.questdb/public/assets/icon-file.svg]
questdb  | 2026-02-10T16:14:22.353149Z I server-main extracted [path=/root/.questdb/public/assets/vendor-DsPrTxrp.js]
questdb  | 2026-02-10T16:14:22.359481Z I server-main extracted [path=/root/.questdb/public/fonts/PPFormula-SemiExtendedBold.ttf]
questdb  | 2026-02-10T16:14:22.361923Z I server-main extracted [path=/root/.questdb/public/fonts/PPFormula-SemiExtendedBold.woff]
questdb  | 2026-02-10T16:14:22.364907Z I server-main extracted [path=/root/.questdb/public/fonts/PPFormula-SemiExtendedBold.otf]
questdb  | 2026-02-10T16:14:22.368585Z I server-main extracted [path=/root/.questdb/public/fonts/PPFormula-SemiExtendedBold.woff2]
questdb  | 2026-02-10T16:14:22.372511Z I server-main extracted [path=/root/.questdb/public/assets/login-background.svg]
questdb  | 2026-02-10T16:14:22.375780Z I server-main extracted [path=/root/.questdb/public/assets/vs/base/browser/ui/codicons/codicon/codicon.ttf]
questdb  | 2026-02-10T16:14:22.383718Z I server-main extracted [path=/root/.questdb/public/assets/vs/base/worker/workerMain.js]
questdb  | 2026-02-10T16:14:22.384102Z I server-main extracted [path=/root/.questdb/public/assets/vs/base/common/worker/simpleWorker.nls.ko.js]
```

### QuestDB version:

9.3.2

### OS, in case of Docker specify Docker and the Host OS:

Debian 13.3

### File System, in case of Docker specify Host File System:

ext4

### Full Name:

kaon

### Affiliation:

hobby project developer

### Have you followed Linux, MacOs kernel configuration steps to increase Maximum open files and Maximum virtual memory areas limit?

- [x] Yes, I have

### Additional context

Attached compose.yaml for reference.

```
services:
  questdb:
    image: questdb/questdb:9.3.1
    container_name: questdb
    ports:
      - "8812:8812"
      - "9000:9000"
      - "9009:9009"
      - "9003:9003"
    networks:
      - questdb
    volumes:
      - .questdb:/root/.questdb
      - .questdb/backup:/root/.questdb/backup
    restart: always

networks:
  questdb:
```

Attached server.conf that is being used since version 6.
[server.conf.txt](https://github.com/user-attachments/files/25215653/server.conf.txt)

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

A valid configuration was treated as invalid during instance startup #6767

To reproduce

QuestDB version:

OS, in case of Docker specify Docker and the Host OS:

File System, in case of Docker specify Host File System:

Full Name:

Affiliation:

Have you followed Linux, MacOs kernel configuration steps to increase Maximum open files and Maximum virtual memory areas limit?

Additional context

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

A valid configuration was treated as invalid during instance startup #6767

Description

To reproduce

QuestDB version:

OS, in case of Docker specify Docker and the Host OS:

File System, in case of Docker specify Host File System:

Full Name:

Affiliation:

Have you followed Linux, MacOs kernel configuration steps to increase Maximum open files and Maximum virtual memory areas limit?

Additional context

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions