Upgrade to RH2020 Failed and Now the RH2017 Content is Not Available in RH2017

Jeff, the backups are now corrupted.  It happened sometime between October and December 2020. 

Peter Grainge, all the files for the topics are intact.  I see them in File Explorer.  I have made backup copies of the project so I can try all the proposed tricks, but all those backups are corrupted.  The last time I had to go into RoboHelp was in December 2020 so I could generate some PDFs for someone.  At that time, the topics were missing, but deleting the CPD file worked and restored them.  But this month I opened RH2017 when the upgrade to RH2020 failed;  I cannot get the CPD deletion trick to work again in RH2017.  The upgrade failed because the CPD file has no information on the topics.   

Rats! Time to look for good backups?

Thank you, Amebr.  However, I waited for three hours and the topics did not appear in the project pod.  

I've never seen all topics vanish, but if you want to try the trick:

1. Open the project in RH2017.

2. In the Project pod, create a new folder. It doesn't matter where and you can call it anything you want.

3. RH will think for a while - leave it for as long as necessary. For very large projects you might need to leave it for an hour or so, but for most projects it should be only a few minutes at most.

4. Once it's done thinking, you can delete the folder. Either the topics and files will be displayed in RH or they won't.

The point of deleting a CPD is to reduce its size.

Are you saying the topics are missing if you look using File Explorer as well? It they are there but just not showing in RoboHelp, try this in copy of the corrupt project. 

If File Explorer shows some topics in the root and then say Folder A, in RoboHelp import one of those topics as if it were a new project. You might see all the topics in the root suddenly appear. Regardless of whether that works also create a Folder A and import one of the topics. I have seen that suddenly make all the topics reappear.

I repeat, do this in a new copy of the project so that if it doesn't work, you still have an untouched copy to see if Amber's trick works.

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Thank you so very much, Jeff.  I will wait for a day or two.  

The size of the CPD may be misleading - it's probably the .fpj (I think that was the extension) - anyway, she's got a technique where you create a new dummy folder inside the project & that has some effect on tricking RH into "finding" all the "missing" topics. Search around or wait until night (as she's Down Under, mate!)

Indeed.  All the topics are missing.  The CPD file used to be 92,712 KB.  When RoboHelp 2017 rebuilds it, the file is only 1052 KB.  I have been suspecting that the project was damaged.  

That doesn't seem to make sense - if you launch RH2017 and then load the project's .xpj file, what do you see? Are your topics all missing? If so, you've got a damaged RH2017 project - iirc  @Amebr has a temp folder trick she's described before to fool RH into realizing all the topics are really still there.