ABAP CONVT_NO_NUMBER Error on SP01 due SP01_WARN Parameter

User parameter SP01_WARN maintained using SAP transaction SU01 should be numeric value otherwise ABAP runtime error CONVT_NO_NUMBER occur on SP01 Spool request selection screen.

One of our SAP users has experienced an interesting error while using SAP transaction SP01 screen (Output controller: Spool request selection screen). He was trying to list the spool requests he had created. SP01 is used for listing the outputs created to print by a specific user or created on a specific printer in general.

On fortunately, he had a dump when he pressed F8 on the screen.
Using ST22 Runtime Error Long Text, ABAP programmer can reach following error data.

Category ABAP Programming Error
Runtime Errors CONVT_NO_NUMBER
ABAP Program SAPLSPOOL_SP01R
Application Component BC-CCM-PRN

Short Text
"X X XX X" cannot be interpreted as a number
An attempt was made to interpret value "X X XX X" as a number.

When I checked the source code extract where the error has occured, I realized that SAP user parameter SP01_WARN is read into a variable and then later used in an ABAP statement where it is compared with an other numeric value.

get parameter id 'SP01_WARN' field gnum.

SP01_WARN parameter is used as a threshold value for numbers of lines in display

When I checked the user parameters using SU01 Maintain Users transaction and go to tab Parameters, I see that a non numeric value was set to SP01_WARN parameter.

SP01_WARN SAP user parameter setting

I switched to change mode on SU01 transaction screen and updated the SP01_WARN parameter value with 0000000000 which resolved the ABAP runtime error.