我需要更新一些软件包，系统建议我更新所有软件包，我照做了（正在进行中）。但现在我无法再编译了，我收到“未找到 pdftex.def”之类的错误。是不是因为更新过程尚未完成？我现在真的很害怕我的文档被损坏了……
2017-04-24 18:23:20 +0000 Warning tlu_ipctask[94383] TLDownload::get_file: response error: 500 read timeout
2017-04-24 18:32:44 +0000 Warning tlu_ipctask[94383] TLDownload::get_file: response error: 500 read timeout
2017-04-24 18:51:22 +0000 Warning tlu_ipctask[94383] TLDownload::get_file: response error: 500 read timeout
2017-04-24 19:00:49 +0000 Warning tlu_ipctask[94383] tlmgr: action update returned an error; continuing.
2017-04-24 19:03:13 +0000 Warning tlu_ipctask[94383] tlmgr: An error has occurred. See above messages. Exiting.
2017-04-24 19:03:15 +0000 Error tlu_ipctask[94383] *** ERROR *** exit status of pid = 94384 was 1