Exchange rates &/& are missing; see long text

What causes this issue?

Exchange rates &/& of exchange rate type & are missing. This exceeds the
maximum number of rates that can be missing.

How to fix this error?

To import the data, in Customizing choose <ZK>Financial Supply Chain
Management -> Treasury and Risk Management -> Basic Functions -> Market
Data Management -> Manual Market Data Entry.</>.
You can also use transaction TBEX to import the market data required
from an Excel file.
You can also increase the maximum number of errors permitted in the
history. The system then increases the size of the sample if market data
is missing.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.