NextJS cannot save to cache on fly.io

2

Assuming that dockerfile contains the following lines:

RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs

COPY --from=builder /app ./

USER nextjs

If so, add a line like the following after the COPY line:

RUN chown -R nextjs:nodejs /app/.next/cache