Bug 460864

SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***


STEPS TO REPRODUCE
1. Downloaded PDF from https://www.lbhf.gov.uk/sites/default/files/section_attachments/medical-assessment-form.pdf 
2. Click "Show Forms" in order to fill form
3. Enter information, click File > Save

OBSERVED RESULT
Okular crashes so fast that I wasn't at first sure that it had time to save the data. Opting to submit a bug report also results in the debugger crashing. 

EXPECTED RESULT
Okular should save the data and allow me to continue entering data?

SOFTWARE/OS VERSIONS
Windows: none
macOS: none
Linux/KDE Plasma: Linux kernel 5.10.0-18-amd64/Debian 11/
(available in About System)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

Operating System: Debian GNU/Linux 11
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2
Kernel Version: 5.10.0-18-amd64
OS Type: 64-bit
Processors: 4 × AMD A10-5700 APU with Radeon(tm) HD Graphics
Memory: 14.9 GiB of RAM
Graphics Processor: AMD ARUBA

Also, after the 1st crash I reopened the file in Okular and my data appeared to have been saved. The 2nd time I clicked File > Save there was no crash, but the 3rd time it did crash. 

I also note that the font size appears to change according to how much text is entered, until I click Show Forms again. This, however, does not appear to crash the application.