The Walkman does not recognize a microSD card.
Try the following measures.
The microSD card may not be inserted correctly.
Remove the microSD card from the Walkman. Then, reinsert the microSD card securely.
The contact pins of the microSD card may be dirty.
Clean the contact pins of the microSD card with a dry cloth or a cotton bud. Then, reinsert the microSD card.
The format of the microSD card is not supported by the Walkman.
Copy all the data on the microSD card onto a computer first. Then, reformat the microSD card on the Walkman.
Use the Walkman to reformat the microSD card. Sony does not guarantee the operation of microSD cards that have been reformatted on other devices such as computers.
The contents of the Help Guide may be subject to change without notice due to updates to the product's specifications.