Salesforce Integration failure

Hi,

Today, the Salesforce integration in my application has suddenly stopped with 'invalid credentails' error message. However, I see credentials are valid and I can even see a successful attempt marked in salesforce log. 

Can someone please help me in resolving this issue.

Appian version: 17.3

Salesforce function: a!sfcQuery()

Salesforce instance: ap6

Salesforce showing successful attempts: 

Stacktrace: 16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) ConnectorRuntimeException [title=Could not connect, com.appian.integration.core.exception.ConnectorRuntimeException: Failed to connect to the external system [key=salesforce]. The site-wide credentials may be incorrect. Please ask an administrator to update the credentials in the Third-Party Credentials page in the Administration Console. Connection failure details: null]
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appian.integration.salesforce.service.SalesforceConnectionFactory.createPartnerConnection(SalesforceConnectionFactory.java:62)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appian.integration.salesforce.service.SalesforceConnectionFactory.createSalesforceService(SalesforceConnectionFactory.java:45)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appian.integration.salesforce.function.QueryFunction.salesforceQuery_appian_internal(QueryFunction.java:49)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at sun.reflect.GeneratedMethodAccessor1244.invoke(Unknown Source)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at java.lang.reflect.Method.invoke(Method.java:498)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.CustomFunction$1.call(CustomFunction.java:797)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.common.ContextClassLoaderSwitcher.runInContext(ContextClassLoaderSwitcher.java:25)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.CustomFunction.evaluate(CustomFunction.java:792)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.CustomFunction.evalDynamic0(CustomFunction.java:240)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.CustomFunction.evalDynamic(CustomFunction.java:228)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.CustomFunction.eval0(CustomFunction.java:200)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.DefaultEvaluable.eval(DefaultEvaluable.java:179)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.process.expression.ExpressionEvaluator.evaluate(ExpressionEvaluator.java:304)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.FunctionCallDelegate$ExternalFunctionCallWithContext.eval(FunctionCallDelegate.java:296)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.FunctionCallDelegate.evalCacheableFunctionCall(FunctionCallDelegate.java:126)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.FunctionCallDelegate.evalFunctionCall(FunctionCallDelegate.java:92)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.AppianScriptContextTop.evalExternalFunction(AppianScriptContextTop.java:349)
16:00:30,510 INFO [stdout] (ajp-/0.0.0.0:8009-7) at com.appiancorp.core.expr.AppianScriptContextChild.evalExternalFunction(AppianScriptContextChild.java:185)