ClassNotFoundException - qStudio cannot connect to Clickhouse

The most common cause of ClassNotFoundException is a problem downloading the correct driver.

I have a pro license and is using QStudio 2.03 on Windows
Do you know why I cannot connect to Clickhouse ?
1/ Host: https:// ...
2/ Server type Clickhouse
I got error when test connection: ClassNotFoundException (ru.yandex.clickhouse.ClickhouseDriver)

How Drivers Work

qStudio has a small number of drivers builtin (mysql/postgresql/kdb..), to prevent requiring a massive installer, most other drivers are downloaded on demand. If you get a ClassNotFoundException either:

• The driver is not downloading - possibly due to connection or firewall issue
• The driver is not being saved to it's directory - file write permissions
• The driver is failing to be loaded dynamically - Java JRE permissions error

To find out which check logs.

Check qStudio Logs

check the logs to see what is happening:

• On windows you can run: C:\Program Files (x86)\TimeStored.com\qstudio-log.bat
• qStudio on windows keeps a log file at C:\Users\{USERNAME}\qStudio
• On mac/linux, you can run

  java -jar qStudio.jar

  to get a version that logs to console.

If you are in any doubt, you can email us the logs. Note you should take care to only email NON-Sensitive information.

Example successful log

Immediately after you click yes, you should get a log similar to that shown below:

ct 16, 2023 12:59:27 PM com.timestored.connections.ConnectionManager statusUpdate INFO: explorer click Connected = false Oct 16, 2023 12:59:27 PM com.timestored.connections.ConnectionManager getConn INFO: getConn Exception server: ServerConfig{name=explorer click, username=explorer, host=localhost, port=0, cstoreType=CLICKHOUSE_COM, database=jdbc:ch:https://play.clickhouse.com:443} Oct 16, 2023 12:59:27 PM com.timestored.qstudio.model.AdminModel$2 run INFO: refreshing explorer click Oct 16, 2023 12:59:45 PM com.timestored.docs.BackgroundDocumentsSaver requestSave INFO: skipping persistOpenDocuments Oct 16, 2023 1:00:00 PM com.timestored.plugins.PluginLoader getCClass INFO: Could not find class already loaded. Refreshing from folders / jars. Oct 16, 2023 1:00:00 PM com.timestored.plugins.Curler downloadFileTo INFO: Downloading https://www.timestored.com/jdbc/drivers/com/clickhouse/clickhouse-jdbc/0.4.6/clickhouse-jdbc-0.4.6.jar -> C:\Users\ray\qstudio\libs\clickhouse-jdbc-0.4.6.jar Oct 16, 2023 1:00:00 PM com.timestored.plugins.PluginLoader installDriver INFO: File downloaded: C:\Users\ray\qstudio\libs\clickhouse-jdbc-0.4.6.jar Oct 16, 2023 1:00:00 PM com.timestored.plugins.PluginLoader getCClass INFO: Could not find class already loaded. Refreshing from folders / jars. SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". SLF4J: Defaulting to no-operation (NOP) logger implementation SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details. Oct 16, 2023 1:00:15 PM com.timestored.docs.BackgroundDocumentsSaver requestSave INFO: skipping persistOpenDocuments