how to fix this issue
Exception #0 (Magento\Framework\Exception\FileSystemException): The path "/var/www/html/rakuten_magento/pub/static/adminhtml/Magento/backend/en_US/requirejs-config.js" is not writable.
Exception #0 (Magento\Framework\Exception\FileSystemException): The path "/var/www/html/rakuten_magento/pub/static/adminhtml/Magento/backend/en_US/requirejs-config.js" is not writable.
<pre>#1 Magento\Framework\Filesystem\Directory\Write->openFile() called at [vendor/magento/framework/Filesystem/Directory/Write.php:361]
#2 Magento\Framework\Filesystem\Directory\Write->writeFile() called at [vendor/magento/module-require-js/Model/FileManager.php:135]
#3 Magento\RequireJs\Model\FileManager->ensureSourceFile() called at [vendor/magento/module-require-js/Model/FileManager.php:63]
#4 Magento\RequireJs\Model\FileManager->createRequireJsConfigAsset() called at [vendor/magento/module-require-js/Block/Html/Head/Config.php:126]
#5 Magento\RequireJs\Block\Html\Head\Config->_prepareLayout() called at [vendor/magento/framework/View/Element/AbstractBlock.php:272]
#6 Magento\Framework\View\Element\AbstractBlock->setLayout() called at [vendor/magento/framework/View/Layout/Generator/Block.php:149]
#7 Magento\Framework\View\Layout\Generator\Block->process() called at [vendor/magento/framework/View/Layout/GeneratorPool.php:93]
#8 Magento\Framework\View\Layout\GeneratorPool->process() called at [vendor/magento/framework/View/Layout.php:365]
#9 Magento\Framework\View\Layout->generateElements() called at [generated/code/Magento/Framework/View/Layout/Interceptor.php:68]
#10 Magento\Framework\View\Layout\Interceptor->generateElements() called at [vendor/magento/framework/View/Layout/Builder.php:129]
#11 Magento\Framework\View\Layout\Builder->generateLayoutBlocks() called at [vendor/magento/framework/View/Page/Builder.php:65]
#12 Magento\Framework\View\Page\Builder->generateLayoutBlocks() called at [vendor/magento/framework/View/Layout/Builder.php:65]
#13 Magento\Framework\View\Layout\Builder->build() called at [vendor/magento/framework/View/Page/Config.php:227]
#14 Magento\Framework\View\Page\Config->build() called at [vendor/magento/framework/View/Page/Config.php:240]
#15 Magento\Framework\View\Page\Config->publicBuild() called at [vendor/magento/framework/View/Result/Page.php:244]
#16 Magento\Framework\View\Result\Page->render() called at [vendor/magento/framework/View/Result/Layout.php:171]
#17 Magento\Framework\View\Result\Layout->renderResult() called at [generated/code/Magento/Backend/Model/View/Result/Page/Interceptor.php:140]
#18 Magento\Backend\Model\View\Result\Page\Interceptor->renderResult() called at [vendor/magento/framework/App/Http.php:120]
#19 Magento\Framework\App\Http->launch() called at [generated/code/Magento/Framework/App/Http/Interceptor.php:23]
#20 Magento\Framework\App\Http\Interceptor->launch() called at [vendor/magento/framework/App/Bootstrap.php:264]
#21 Magento\Framework\App\Bootstrap->run() called at [pub/index.php:30]
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