We have made some internal changes to how mongosh processes the JavaScript code that it receives as input. (This affects the built-in shell in Compass and VSCode playground as well, if it matters). I don’t think we have previously documented the limitations that we were imposing on users. Luckily, there’s only few left, and it’s not going to be a common occurrence for people to encounter them, but we should document them: The results of database calls, directly or indirectly through other functions, cannot be used in three contexts, namely, inside class constructor functions, inside non-async generator functions, and inside callbacks to array.sort() . As a workaround, wrapping the access to db results in async functions or using async generator functions works, respectively. Concretely, this means: // For constructors: // ------------------------ // This will not work class SomeClass { constructor() { this .value = db.coll.find(); } } // Neither will this function listEntries() { return db.coll.find(); } class SomeClass { constructor() { this .value = listEntries(); } } // But this can be used instead, if it also fits the purpose here: class SomeClass { constructor() { this .value = (async() => { return db.coll.find(); })(); } } // For generator functions: // ------------------------ // This will not work function* someGenerator() { yield db.coll.find(); } // Neither will this function listEntries() { return db.coll.find(); } function* someGenerator() { yield listEntries(); } // But this can be used instead, if it also fits the purpose here: function listEntries() { return db.coll.find(); } async function* someGenerator() { yield listEntries(); } // For array.sort: // ------------------------ // This will not work db.getCollectionNames().sort((coll1, coll2) => { return db[coll1].estimatedDocumentCount() - db[coll2].estimatedDocumentCount()) }); // But this approach can be used instead (and is often more performant): db.getCollectionNames().map(collName => { return { collName, size: db[collName].estimatedDocumentCount() }; }).sort((coll1, coll2) => { return coll1.size - coll2.size; }).map(coll => coll.collName);