I’m adding the workerSource pdfjsLib.GlobalWorkerOptions.workerSrc = ‘./pdf.worker.js’; but still showing this warning in the console Setting up fake worker. It works only when referencing the original file in github Answer I had the issue because I already had an instance of the pdfWorker created when the file pdf.worker.js was loaded, I fixed it by adding this globalThis.pdfjsWorker = null; just