Safari quitting instantly

Hello!

I have tried to use my MacBook Pro this evening and suddenly I am unable to use Safari. If I click on Safari, it briefly flashes up and then within a second, shows the following error message, followed by pages of ‘thread’ details. What can I do? Grateful for any ideas.

Process:         Safari [1035]

Path:          /Applications/Safari.app/Contents/MacOS/Safari

Identifier:       com.apple.Safari

Version:         14.0.3 (16610.4.3.1.7)

Build Info:       WebBrowser-7610004003001007~5

Code Type:        X86-64 (Native)

Parent Process:     ??? [1]

Responsible:       Safari [1035]

User ID:         501

Date/Time:        2021-04-24 21:48:27.630 +0100

OS Version:       macOS 11.2.3 (20D91)

Report Version:     12

Bridge OS Version:    5.2 (18P4347)

Anonymous UUID:     298B208D-BE46-1537-8736-BBC6BBBC87FE

Time Awake Since Boot: 1700 seconds

System Integrity Protection: enabled

Crashed Thread:     0  Dispatch queue: com.apple.main-thread

Exception Type:     EXC_CRASH (SIGABRT)

Exception Codes:     0x0000000000000000, 0x0000000000000000

Exception Note:     EXC_CORPSE_NOTIFY

Application Specific Information:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[2]'

terminating with uncaught exception of type NSException

abort() called