Getting Nosuchsessionexception when we run multiple testclasses through testng.xml file

This is occuring when we run multiple scripts through testng.xml .if we run scripts saperately its working fine.Not sure what could be the reason for this

Caused by: org.openqa.selenium.NoSuchSessionException: Session ID is null. Using WebDriver after calling quit()?
Build info: version: ‘3.141.59’, revision: ‘e82be7d358’, time: ‘2018-11-14T08:17:03’
System info: host: ‘INHYNVTHALLAPE1’, ip: ‘10.91.150.159’, os.name: ‘Windows 10’, os.arch: ‘amd64’, os.version: ‘10.0’, java.version: ‘1.8.0_144’
Driver info: driver.version: AndroidDriver
at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:125) ~[selenium-remote-driver-3.141.59.jar:?]
at io.appium.java_client.remote.AppiumCommandExecutor.execute(AppiumCommandExecutor.java:239) ~[java-client-7.0.0.jar:?]
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:552) ~[selenium-remote-driver-3.141.59.jar:?]
at io.appium.java_client.DefaultGenericMobileDriver.execute(DefaultGenericMobileDriver.java:42) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.AppiumDriver.execute(AppiumDriver.java:1) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.android.AndroidDriver.execute(AndroidDriver.java:1) ~[java-client-7.0.0.jar:?]
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:323) ~[selenium-remote-driver-3.141.59.jar:?]
at io.appium.java_client.DefaultGenericMobileDriver.findElement(DefaultGenericMobileDriver.java:62) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.AppiumDriver.findElement(AppiumDriver.java:1) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.android.AndroidDriver.findElement(AndroidDriver.java:1) ~[java-client-7.0.0.jar:?]
at org.openqa.selenium.remote.RemoteWebDriver.findElementByXPath(RemoteWebDriver.java:428) ~[selenium-remote-driver-3.141.59.jar:?]
at io.appium.java_client.DefaultGenericMobileDriver.findElementByXPath(DefaultGenericMobileDriver.java:152) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.AppiumDriver.findElementByXPath(AppiumDriver.java:1) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.android.AndroidDriver.findElementByXPath(AndroidDriver.java:1) ~[java-client-7.0.0.jar:?]
at org.openqa.selenium.By$ByXPath.findElement(By.java:353) ~[selenium-api-3.141.59.jar:?]
at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:315) ~[selenium-remote-driver-3.141.59.jar:?]
at io.appium.java_client.DefaultGenericMobileDriver.findElement(DefaultGenericMobileDriver.java:58) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.AppiumDriver.findElement(AppiumDriver.java:1) ~[java-client-7.0.0.jar:?]
at io.appium.java_client.android.AndroidDriver.findElement(AndroidDriver.java:1) ~[java-client-7.0.0.jar:?]
at org.openqa.selenium.support.ui.ExpectedConditions$20.apply(ExpectedConditions.java:577) ~[selenium-support-3.141.59.jar:?]
at org.openqa.selenium.support.ui.ExpectedConditions$20.apply(ExpectedConditions.java:573) ~[selenium-support-3.141.59.jar:?]
at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:249) ~[selenium-support-3.141.59.jar:?]
at mobile.android.functions.Common.invisibilityOfElementLocated(Common.java:141) ~[classes/:?]
at mobile.android.functions.AppLogin.Login(AppLogin.java:48) ~[classes/:?]
at mobile.android.preconditions.PRE_LoginToApp.loginToAPP(PRE_LoginToApp.java:42) ~[classes/:?]
at mobile.android.preconditions.PRE_LoginToApp.call(PRE_LoginToApp.java:71) ~[classes/:?]
at mobile.android.preconditions.PRE_LoginToApp.call(PRE_LoginToApp.java:1) ~[classes/:?]
at com.gtnexus.testautomation.runtime.core.ScriptRunner$1.apply(ScriptRunner.java:196) ~[runtime-6.0.0-SNAPSHOT.jar:6.0.0-SNAPSHOT]
… 28 more
[INFO ] 2019-07-24 16:25:13.147 - Screenshot successfully attached! Name = Testscript Skipped Point
[WARN ] 2019-07-24 16:25:13.147 - driver is not active for a screenshot
[INFO ] 2019-07-24 16:25:13.147 [GTAFPlatform] GTAFTestListenerAdapter - info - DriverScript TestCache.isOpen=true
[INFO ] 2019-07-24 16:25:13.148 [GTAFPlatform] GTAFTestListenerAdapter - info - DriverScript Resetting Test Context…
[35m[HTTP] [39m [37m–> [39m [37mPOST [39m [37m/wd/hub/session/66a091ef-3902-456b-9f19-035d81dcbb48/log [39m
[35m[HTTP] [39m [90m{“type”:“logcat”} [39m
[35m[HTTP] [39m [37m<-- POST /wd/hub/session/66a091ef-3902-456b-9f19-035d81dcbb48/log [39m [32m200 [39m [90m167 ms - 1493181 [39m
[35m[HTTP] [39m [90m [39m
[35m[HTTP] [39m [37m–> [39m [37mDELETE [39m [37m/wd/hub/session/66a091ef-3902-456b-9f19-035d81dcbb48 [39m
[35m[HTTP] [39m [90m{} [39m
[35m[Appium] [39m Removing session 66a091ef-3902-456b-9f19-035d81dcbb48 from our master session list
[35m[HTTP] [39m [37m<-- DELETE /wd/hub/session/66a091ef-3902-456b-9f19-035d81dcbb48 [39m [32m200 [39m [90m1956 ms - 14 [MODULE=RUNTIME,ACTION=SAVE_RESULTS,CLASS=SCRIPTSESSION]- Total Execution Time(in Seconds): 66
[MODULE=RUNTIME,ACTION=SAVE_RESULTS,CLASS=SCRIPTSESSION]- Saving Results PLEASE WAIT…
[39m