MySQL Bugs: #119271: Connector/J fails to accept legacy value zeroDateTimeBehavior=convertToNull on multi-host URLs (failover), but works on

Bug #119271	Connector/J fails to accept legacy value zeroDateTimeBehavior=convertToNull on multi-host URLs (failover), but works on
Submitted:	30 Oct 2025 11:14	Modified:	14 Jan 21:41
Reporter:	Wu Zhengyi (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / J	Severity:	S3 (Non-critical)
Version:	All	OS:	Any
Assigned to:	Filipe Silva	CPU Architecture:	Any
Tags:	backward-compatibility, failover, multi-host, properties, zeroDateTimeBehavior

Description:
When using a multi-host JDBC URL (failover) with the legacy property value zeroDateTimeBehavior=convertToNull, the driver throws an exception stating the only acceptable values are CONVERT_TO_NULL, EXCEPTION, or ROUND. The same property/value works with a single-host URL.
Root cause:
Legacy value translation is applied only per-host in fixHostInfo() via replaceLegacyPropertyValues(hostProps).
In the failover path, FailoverConnectionProxy initializes properties from ConnectionUrl.getConnectionArgumentsAsProperties(), which returns the global properties map (this.properties) that has not been passed through replaceLegacyPropertyValues.
As a result, convertToNull is not normalized to CONVERT_TO_NULL and enum parsing fails in EnumPropertyDefinition.
Impact:
Backward-compatible URLs that rely on convertToNull fail in multi-host scenarios, but succeed in single-host scenarios, creating inconsistent behavior.
Exception (abridged):
com.mysql.cj.exceptions.CJException: The connection property 'zeroDateTimeBehavior' acceptable values are: 'CONVERT_TO_NULL', 'EXCEPTION' or 'ROUND'. The value 'convertToNull' is not acceptable.

How to repeat:
Use a JDBC URL with two hosts and legacy value:
jdbc:mysql://host1:3306,host2:3306?useSSL=false&zeroDateTimeBehavior=convertToNull
Attempt to connect (e.g., via DriverManager.getConnection).
Observe: connection fails with WrongArgumentException as above.
Control:
Using a single host URL with the same parameters succeeds:
jdbc:mysql://host1:3306?useSSL=false&zeroDateTimeBehavior=convertToNull

Suggested fix:
Normalize legacy property values in the global properties map, not only in per-host maps.
Concrete change:
In com.mysql.cj.conf.ConnectionUrl.collectProperties(...), after expanding and injecting properties, call:
fixProtocolDependencies(this.properties) [optional but consistent], and
replaceLegacyPropertyValues(this.properties)
so that getConnectionArgumentsAsProperties() returns already-normalized values used by FailoverConnectionProxy and other multi-host connection proxies.
Rationale:
Single-host paths use HostInfo built through fixHostInfo(), which already calls replaceLegacyPropertyValues(hostProps).
Multi-host paths use global properties; normalizing them ensures parity between single- and multi-host behaviors.
Compatibility:
Safe; only broadens acceptance of legacy values in global properties, maintaining existing behavior for per-host properties.

Thank you for your interest in MySQL Connector/J and for taking the time to file this report.

Verified as described.

https://github.com/mysql/mysql-connector-j/pull/119

Thank you for your contribution, but the issue is already being addressed internally.

Contribution submitted via Github - fix Bug #119271: Connector/J fails to accept legacy value zeroDateTimeBehavior=c 
(*) Contribution by Wu Zhengyi (Github wuzhengyi, mysql-connector-j/pull/119#issuecomment-3638095843): 
I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.
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| From | ***@***.***> |
| Date | 12/09/2025 22:54 |
| To | mysql/mysql-connector-j ***@***.***> |
| Cc | Zane ***@***.***>,
Author ***@***.***> |
| Subject | Re: [mysql/mysql-connector-j] fix Bug #119271: Connector/J fails to accept legacy value zeroDateTimeBehavior=convertToNull on multi-host URLs (failover), but works on (PR #119) |
mysql-oca-bot left a comment (mysql/mysql-connector-j#119)

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Contribution: git_patch_3074257288.txt (text/plain), 3.90 KiB.

Posted by developer:
 
 Added the following note to the MySQL Connector/J 9.6.0 release notes:		
 
Using a multihost JDBC URL with the property value zeroDateTimeBehavior=convertToNull, resulted in an exception.
As of this release, legacy values are normalized in both host and general properties in ConnectionUrl.
Our thanks to Wu Zhengyi and the team at AliBaba for the contribution.