can not connect the target;read out protection is activated

[ALAMUSI]

问题描述：我电路板上使用的单片机是STM32H750系列，电路板工作正常; 始终使用STLINK工具下载程序; 最近，MCU经常出现无法下载程序的问题。具体现象是STLINK工具弹窗显示“读出保护已激活”。关闭弹窗后，出现“无法连接目标”消息，计算机与MCU失去连接。 我在网上搜索了很多解决方案，但没有一个能够解决它。最后，我不得不用新的MCU替换MCU。 更换后，它工作正常，下载程序没有问题，但下载几次后问题再次出现。我非常苦恼，

[STTwo-32]

Hello @ALAMUSI and welcome to the ST Community :smiling_face_with_smiling_eyes:. 

To give more visibility to your post, i suggest you use English for your posts which is the official language of this forum. I translated your post using Google translate and here is the text I received:

"Problem description: The microcontroller used on my circuit board is the STM32H750 series, and the circuit board works normally; I always use the STLINK tool to download programs; recently, MCUs often have problems downloading programs. The specific phenomenon is that the pop-up window of the STLINK tool displays "Readout protection is activated". After closing the pop-up window, a "Unable to connect to target" message appears, and the computer loses connection with the MCU. I searched many solutions online but none of them can solve it. Finally, I had to replace the MCU with a new one. After replacing it, it worked fine and downloaded the program without problems, but after downloading it a few times the problem reappeared. I am very distressed."

I think you have enabled the readout protection level2. In this case, you can't connect anymore to this MCU. for more details, take a look at the part 4.5.3 of the RM0433 for more details.

Best Regards.

STTwo-32

[ALAMUSI]

Thank you very much for your reply. Currently, I am using an unconventional method to connect it to my computer. Although it may not be a long-term solution, it can still solve the current needs; The fundamental reason for this issue may be gradually studied later