Regarding the new version of QQ installer running after 2020 under XP system (or other Tencent programs, such as Tencent Manager, which have not been tested), there is an error message that "the installation package may be illegally changed, resulting in installation failure", which is caused by the lack of root certificate.

Simply put, the new version of QQ installer has enabled a new digital signature, and the root certificate associated with its digital signature does not exist on XP system by default, so verification will only lead to installation failure.

Solution: First, install the root certificate update (KB93 1 125) as mentioned in Deng Yali's folding answer, and then manually install the root certificate of this installer separately.

The specific method for manually installing the root certificate is as follows:

Right-click the properties of QQ installer, click Digital Signature-Details, click View Certificate, click DigiCert root CA at the top of the certificate path, click View Certificate, click Install Certificate, and then confirm the installation certificate step by step (XP can install certificates in trusted root certificate authorities by default).

After the certificate is installed, the digital signature of the file is normal (it can also be found in IE Options-Internet Options-Certificate, or run Certificate Manager (certmgr.msc) to find DigiCert in the trusted root certificate), and the installation program can also run normally.

For details, please refer to the answer to my other question: network link.