Upgraded to Lightroom Classic V10 - Can work in "Library" and "Develop" modules. When use the collection in "Slideshow" module - the error message "Load library failed with error 87: The parameter is incorrect". I checked and updated graphics cards and error message continues. Uninstalled LRC and re-installed and error message continued. ????
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.
I suspect a GPU driver issue, perhaps out if date.
Or a plug-in. Some third party plug-ins started being an issue at v10.0