Step 1: If the customer says ledger report or data is not matching, then check dashboard values first.  Sales, Purchase, receipt, payment, Outstanding. Mostly will get the difference in Outstanding. 

Step2: To find issues go to the outstanding receivable / payable> filter by ledger group> match the group values. 

https://help.bizanalyst.in/biz-analyst-manual/support/data-on-my-phone-is-not-matching-with-tally/how-to-match-numbers-1/untitled

Step 3: In the  group will get the difference> then match the values by ledger. 

Step 4: In ledger check all the entries day by day> will get the difference.

Step 5: After getting the difference the entry will be missing from the ledger report. So after this go to the daybook> add filter of missing date> and search the entry by the amount or ledger.

Step 6: Then you will get the entry , but it will show differences with masters. Need to match masters then will get the master name difference in stock item, ledger or with any special characters. 

Step 7: In this case masters are not updating in the current desktop version. So here we are giving custom builds to the customers. That build will be in version 7 only. 

Step 8: Install the custom build in users desktop and resync all the companies. After resync the issue will be resolved.