If you're using the Postman Chrome app,
1. We strongly suggest you move to the native apps (https://www.postman.com/apps) due to the deprecation of our official chrome extension for (OSX / Windows / Linux) and the native apps support a lot more features.
2. Before reinstalling, head to chrome://indexeddb-internals/ and search for "fhbjgbiflinjbdggehcddcbncdddomop". There will be two folders listed - backup the contents of these folders.
3. Reinstall (navigate to this link and reinstall the latest version) and move the backup to its original location.