You want a solvent not containing any acidic hydrogens or other functional groups sensitive to bases. Such solvents include hydrocarbons (like hexane/toluene) and ethers (THF/Et2O).
Chlorinated hydrocarbons (DCM, chloroform) might react, so don't use them just to be safe. Esters, alcohols and ketones and any solvents not properly dried are directly unsuitable.