[Help] My virtual login tulinux cannot be updated. Why?

[Help] My virtual login tulinux cannot be updated. Why? -- Linux general technology-Linux technology and application information. For details, refer to the following section. The operation is as follows:
System -- system Management-update Manager

UP-TO-DATE appears

Then I check. Then download ..

However, after the progress is completed, the system prompts "Cannot download deb http: // ******" (The address is too long, and I use an asterisk to indicate it)

Below is

The following attachment has

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