When logging into Strategy Library 2019, the following error may appear:
"The item you are trying to access cannot be found. It may have been deleted."

In the DSSErrors.log file, a similar entry can be found:
Object with ID '98B67F621DCD4CA081971B2DA4DC6F82' and type 52 (Link) is not found in metadata. It may have been deleted.
http://<Library Server>:<port>/MicroStrategyLibrary/app.
This is an identified defect in Strategy Library 2019 caused by a corrupted profile link object in the metadata.
This issue is addressed in Strategy Library 2019 Update 3. Upgrade to the latest version of Strategy to take advantage of the fix.
As a short term solution, you can re-upgrade the 2019 metadata to correct the metadata inconsistency and resolve the issue.