QTP does not throw any error but can not identify the objects.
1.Check the builds if you have picked up correct build of application to test. This is one of the basic issue of today's testing process.Also it is always better to check the QTP build number.Here is a document on how to find out build.
2. Check the Zoom level. Sometimes increasing the zoom level will solve this issue.Mostly this issue occurs when we work on Pega application. Pega's layered approach gets hidden when it is not 100%. Sometimes to identify an element we need to Zoom in 125%.
3. Tabbed browser is not supported. Uncheck the Tabbed browsing option so that QTP/UFT can run smoothly.
4. QTP/UFT stops just after few lines may be 3 to 4 line in debug mode.F10 does not move the cursor to the next line.
The best possible issue could be lack of space in the drive where QTP/UFT is installed. Increase the space to accommodate the temp files.
Check for the RAM availability. If many processes are trying to get executed at the same time, QTP may get starvation issue.
If the above does not work out,reset the QTP/UFT to factory settings. Lastly you can uninstall and install it freshly.
5. Type casting error: It happens when we try to read data from datatable. It must take the parameter in a string but sometimes it fails to identify the data as a string.
Error code Error:Parameter <<VariableName>> should be srring but undefined.
Check the datatable column and convertible methods.Also check if the variable is defined or not.
6. Remote execution is fine and smooth so as local but even if you have good citrix net speed and local net speed you may face slow execution issue. QTP behaves like dead slow.
Similar like point no-4, Check for RAM size and available applications running along with citrix. Less RAM size and many parallel process may slow down the QTP/UFT execution process.
7. Excel connectivity issue. Every time office is upgraded to 2007 to 2010 to 2013 to 2017, QTP/UFT can not read execl. It stops,hangs,freezes during execution.
The best possible way to resolve this issue is to create connectivity with excel using ADODB.
Here is a good tutorial on the same.
8.Recored script does not work properly.Mostly while selecting values from drop downs. - Try to use descriptive programing. Most of the cases get resolved by this. if this does not solve this issue. try select (1) or select(#1).
9. We have licenses across teams. Client has given us total 10 licenses. When our team is trying to access QTP, QTP is throwing error saying no QTP available to use. This is a common issue in our team in our day to day use. Many of us do not shutdown/close QTP to terminate the session. We just lock the Screen to go home. This time UFT/QTP session is unused but can not be accessed.
To resolve the issue we need to use locked concept of QTP/UFT.In that case the licenses we will be locking will be available for our use.Other team can use remaining licenses(total licennses-locked licenses)
Here is a link that helps -https://community.hpe.com/t5/Unified-Functional-Testing/Locking-Code-for-QTP-QC-concurrent-licence/td-p/4488389
we can verify qtp software dump->license server -utilities ->winadmin.exe who are using the licenses.