The digitally signed certificate needs to be reinstalled. According to the query results, when the user installs nx 1926 program, there is a prompt that the digital signature is invalid, and the user needs to reinstall the digital signature certificate, which can be downloaded and installed in nx official website. UGNX is a product engineering solution produced by SiemensPLMSoftware, which provides digital modeling and verification means for users' product design and processing.