We are trying to upgrade the spring version to 5.X, but since was uses javx.validation version 1.0.0 and spring uses 1.1.0, we are not able to launch application,

Also found some workarounds by changing the class loader to PARENT_LAST to load the jar form module, but due to this none of the ibm and was jar are loading and facing data source lookup exceptions

Can you please help me if there are any solution for using spring 5 with was8.5

As you see in the spring document below, spring v5 is supposed to run on JavaEE7 runtime as a minimum.

https://docs.spring.io/spring-framework/docs/5.2.20.RELEASE/spring-framework-reference/overview.html#overview

As of Spring Framework 5.0, Spring requires the Java EE 7 level (e.g. Servlet 3.1+, JPA 2.1+) as a minimum

And WASv8.5 is JavaEE6 compliant, thus, you need to migrate the environment to WASv9 which supports JavaEE7 compliant application.

https://www.ibm.com/docs/en/was-nd/8.5.5?topic=overview-specifications-api-documentation#rovr_specs__anyappl

https://www.ibm.com/docs/en/was/9.0.5?topic=specifications-java-ee-7-programming-model-support