# Android Studio error : Cannot open a library at 'FileMapping(from=....core.jar, to=....jetified-core.jar)

**URL:** <https://forums.rocket.chat/t/android-studio-error-cannot-open-a-library-at-filemapping-from-core-jar-to-jetified-core-jar/2735>\
**Category:** Community Support\
**Created:** [December 19, 2018, 6:08am UTC](https://forums.rocket.chat/t/android-studio-error-cannot-open-a-library-at-filemapping-from-core-jar-to-jetified-core-jar/2735 "2018-12-19T06:08:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rajeev](https://avatars.discourse-cdn.com/v4/letter/r/ec9cab/32.png) [@Rajeev](https://forums.rocket.chat/u/Rajeev)\
**Post date:** [December 19, 2018, 6:08am UTC](https://forums.rocket.chat/t/android-studio-error-cannot-open-a-library-at-filemapping-from-core-jar-to-jetified-core-jar/2735/1 "2018-12-19T06:08:38Z")

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Hi,  
I am trying to use the Rocket.Chat APIs in one of my projects. But after adding the jars and completing the gradle things when I tried to run the App, I am getting the error like "Cannot open a library at ‘FileMapping(from=/home/rls/AndroidStudioProjects/RocketChatIntegration/my-app-android/app/libs/core.jar, to=/home/rls/.gradle/caches/transforms-1/files-1.1/core.jar/8bd996c777fadbbb76d825eb83614401/jetified-core.jar)’  
"  
Any suggestions why this is coming. Please suggest.