The group's organic service revenue, however, rose 1.7 percent, while the telco's adjusted EBITDA came in 13 percent higher at €7.4 billion.
Shares jumped 4.12% to 224.95p in early trading.
The company said the increased forecast, which implies core earnings of 14.75-14.95 billion euros, reflected stronger than expected underlying revenue growth in Europe and a later than anticipated launch of a new entrant in Italy.
The world's second-largest mobile carrier by subscribers said in the six months ended September 30 that it made a pretax profit of 2.16 billion euros ($2.52 billion), up 55% on the same period a year earlier.
Excluding the impact of net roaming declines in Europe and the benefits in the United Kingdom from the introduction of handset financing and regulatory settlements, organic adjusted EBITDA increased 9.3%.
Despite the profits swing, group revenue slipped 4.1% to 23.08 billion euros (£20.58 billion) following the consolidation of its Vodafone Netherlands business and the creation of joint venture VodafoneZiggo.
"In India competition remains intense", noted Colao.
The London-listed group agreed in March to merge its Vodafone India division with Idea Cellular in order to create India's largest telecoms operator and fight ultra-competitive new player Reliance Jio.
"We are able to report a strong financial performance, with substantial ... profit growth, and we are raising our financial outlook for the year", said chief executive Vittorio Colao.
"We are making good progress in securing regulatory approvals for our merger with Idea Cellular".
"Enterprise revenues continue to grow, led by our Internet of Things (IoT), Cloud and Fixed services, and for the second year running we achieved an absolute reduction in our operating costs".
Vodafone lifted its full-year guidance for growth in underlying profit - as measured by earnings before interest, taxes, depreciation and amortisation (ebitda) - to 10% from 4%-8%.