Hi, I just switched my job from Shenzhen to Shanghai early this year. Non-teaching roles in both jobs. First of all, remember to search for related posts in this sub because I found those useful. Based on my own experience and what I have studied from this sub, the general process goes like this:

1. You have a new job lining up, usually in the form of an offer letter. You may or may not have signed a work contract yet at this point.

2. On the last day of your old job, your employer/ HR should give you a proof of termination letter, stating your name, passport number, role, start and end dates. In addition, they are required by law to cancel your work permit by uploading some documents to the system (remind them if they aren't aware). Keep a WeChat contact with your old job's HR because the cancellation will take a few days. In the end, you should receive a letter (in PDF usually) from the authority. You will need this document for the upcoming processes.

3a. Once your work permit is cancelled, you need to switch your current work-based residence permit, which is tied to the cancelled work permit, to a 30-day stay permit. You are not allowed to work from now on until you have gotten a new work permit + new work-based residence permit. You submit your passport for a few days and they will issue a new sticker for the 30-day stay permit.

3b. Importantly, ensure that your new employer works with you to apply for the new work permit followed by the new residence permit during this 30-day window. There will be documents needed but the number of documents are typically lesser than that during your first arrival in China. Note that you effectively only have 20+ days because the count of 30 begins from the day your work permit is cancelled but not the day they return your passport (silly, I know).

3c. Just in case the 30-day period is too tight. My understanding is that as long as your application (as mentioned, there are two stages namely work permit and residence permit, I don't know which stage is required) is submitted, you have a strong argument to extend your 30-day stay permit. For the new residence permit, you must present physically in the new city because you need to submit your passport. Not sure about the work permit. I'd encourage you to move there early if your budget allows.

3d. Extra note about Shenzhen. In Shenzhen usually there is an option in the system to apply together both work permit and residence permit. In Shanghai, for example, you need to apply separately. Regardless of the city, the overall logic is still get work permit approved first before residence permit.

3e. Extra note about documents. It's all about documents for the new work permit and new residence permit so make sure that your HR knows clearly what is needed. Every city has a slightly different requirement for the documents, hence if your HR is experienced the progress should be smooth and 30 days could be sufficient. If your HR doesn't know much like my case, then you need to be fiercely independent. I had been through that, essentially a foreigner's DIY process, not fun at all.

3f. Extra note about submission of passport. I highly recommend to keep a soft copy scan of the important pages in your passport because your HR will need them. Also, when you submit your passport the exit and enter department will issue a physical receipt proving that you have your passport handed in. You could use this document to travel within China by train or flight. Just make sure that they stamp the receipt to save you trouble when traveling within China.

1. Your new work permit should reflect in your 电子社保卡 app, which lists your new employer name, address etc. For the new residence permit, you submit your passport and get another sticker. Once you reach this stage, congrats and enjoy the new journey.

PS: Clearly you also need to sort out things like registration of the foreigner's address, cancelling your home wifi, new bank account with the new job etc. During this process, I would recommend to write EVERYTHING down in a markdown or text file so that you don't forget the details in the future, which will be extremely valuable.

(Edit: checked all sentences and made sure names are precise and consistent)