VM 4 migration error 'JRequest' not found

[vmproblem1]

I'm trying to migrate my site from J3.10.11 to J4.2.1.
PHP 7.4.30
Database Mysql 5.7.36-39-log
Virtuemart 4.0.6

When I navigate Virtuemart pages I get this error message:
0 Class 'JRequest' not found
What's the problem?

[ssc3]

I'm trying to migrate my site from J3.10.11 to J4.2.1.
PHP 7.4.30
Database Mysql 5.7.36-39-log
Virtuemart 4.0.6

When I navigate Virtuemart pages I get this error message:
0 Class 'JRequest' not found
What's the problem?

JRequest no longer works in Joomla 4. JRequest should be replaced by vRequest

The error may be caused by a plugin that has not been updated.

In the Joomla admin try setting "Debug System" to "Yes" and "Error reporting" to "Maximum".

That might tell you which plugin is the source of the problem.

[Jumbo!]

It has nothing to do with VirtueMart.

Class "JRequest" does not exist in Joomla 4. You must have an old Joomla 3 extension or template installed on your site, which is incompatible with Joomla 4.